;RC 


F.  Foster 


EDUCATION  DEPT, 


d  -^  o 


F."  Foster 


STUDENT'S  MANUAL  OF  EXERCISES 
IN  ELEMENTARY  BIOLOGY 


BY 
BENJAMIN  C.  GRUENBERG 

CHAIRMAN    DEPARTMENT   OF    BIOLOGY,   JULIA    RICHMAN    HIGH    SCHOOL 

NEW    YORK 

AND 

FRANK  M.  WHEAT 

CHAIRMAN    DEPARTMENT   OF    BIOLOGY,    GEORGE   WASHINGTON    HIGH    SCHOOL 

NEW    YORK 


GINN  AND  COMPANY 

BOSTON    •    NEW  YORK    •    CHICAGO    •    LONDON 
ATLANTA    •    DALLAS    •    COLUMBUS    •    SAN  FRANCISCO 


H  i> 

TO  THE  STUDENT 

In  order  to  get  the  most  value  out  of  your  study  of  living  things  it  is  necessary  to  keep  a  record  of 
observations  and  ideas  as  you  go  along. 

It  is  the  purpose  of  this  Manual  to  help  you  keep  a  systematic  record,  as  well  as  to  guide  you  in 
discovering  the  facts  that  you  will  need  for  the  more  important  ideas.  You  will  of  course  get  more  facts 
and  more  ideas  than  this  Manual  calls  for.  You  will  sometimes  have  to  make  notes  on  loose  sheets 
of  paper  or  in  a  plain  composition  book.  You  will  find  it  helpful  to  make  short  abstracts  of  what 
you  read  in  your  textbook  or  in  other  books.  You  will  find  it  well  worth  while  to  record  demonstrations 
made  in  the  laboratory  by  the  teacher  or  by  other  students,  and  observations  made  at  home,  out  of 
doors,  or  in  the  classroom,  by  yourself  or  by  others. 

Begin  your  work  by  dating  it.    Where  work  carries  over  from  day  to  day,  date  every  entry. 

Read  all  the  directions  for  an  exercise  through  before  doing  any  of  the  work,  making  sure  that 
you  understand  what  you  are  trying  to  find  out  and  just  what  you  are  going  to  do. 

Make  your  record  as  you  go  along  instead  of  waiting  until  the  work  is  completed.  A  large  part 
of  the  value  of  a  scientific  record  is  in  its  being  made  while  the  observation  is  fresh  in  mind,  before 
there  is  time  to  forget  it  or  to  confuse  it  with  other  observations. 

With  most  of  the  exercises  there  are  questions  to  think  about.  These  questions  are  not  meant  to 
find  out  how  much  you  already  know,  but  to  show  you  how  our  understanding  grows  by  combining  facts 
into  bigger  ideas,  and  how  ideas  are  put  to  work.  So  in  writing  your  answers  it  would  be  well  to  give 
your  reasoning  instead  of  merely  your  final  conclusion  or  a  simple  Yes  or  No. 


COPYRIGHT,    1921,    BY    BENJAMIN    C.    GRUENBERG    AND    FRANK    M.    WHEAT 

321.11 


TO  THE  TEACHER 

It  is  the  purpose  of  this  Manual  to  be  of  direct  help  to  teachers  and  students  of  biology.  It  is  not 
intended,  however,  to  be  an  automatic  instrument  to  be  placed  in  the  hands  of  students  abandoned  to 
their  own  resources  and  good  fortune.  It  will  be  necessary  for  the  teacher  to  plan  the  work  in  accord- 
ance with  available  material  and  with  local  conditions.  There  are  more  exercises  than  most  classes  will 
be  able  to  finish  ;  there  will  arise  occasions  when  exercises  suggested  in  the  Manual  for  Teachers  will 
appear  more  urgent  than  any  here,  and  there  will  be  other  occasions  when  totally  new  exercises  will  be 
most  appropriate.  The  exercises,  like  the  topics  in  the  "  Elementary  Biology,"  can  most  profitably  be 
arranged  in  the  order  best  suited  to  local  conditions  or  to  the  interests  of  the  teacher. 

The  exercises  are  varied  in  form.  Some  are  strictly  experimental  ;  others  are  observational  ;  some 
call  for  the  collection  and  organization  of  facts  already  in  the  possession  of  the  pupils  or  of  the  com- 
munity, utilizing  "  what  everybody  knows."  In  every  case  the  exercise  is  designed  to  be  a  project  in 
finding  out  something,  usually  something  more  comprehensive  and  more  significant  than  mere  matters 
of  fact.  Accordingly  the  projects  permit  of  a  great  variety  of  adaptations  to  the  conditions  and  needs  of 
different  localities  or  students.  There  are  home  and  field  and  community  exercises  as  well  as  strictly 
laboratory  exercises.  Moreover,  some  of  the  "  laboratory  "  exercises  call  for  living  material  in  the  form 
of  the  students  themselves,  suggesting  that  biology  can  be  something  very  immediate  and  intimate  as 
well  as  exotic  and  objective.  There  is  a  wide  choice  of  materials  and  equipment  and  also  of  execution. 

Some  of  the  exercises  emphasize  the  need  for  large  masses  of  data  or  the  need  for  cooperation 
among  many  observers.  In  all  cases  the  social  aspects  of  science,  both  in  the  sense  of  its  origins  in 
common  experience  and  in  the  sense  of  its  application  to  common  problems,  will  be  readily  brought  to 
the  mind  of  the  students. 

Although  only  a  very  few  of  the  exercises  are  marked  "  Demonstration,"  many  of  the  others  will  be 
best  executed  by  the  teacher  or  by  a  single  student  or  group  of  students,  with  all  the  others  making 
notes.  In  some  cases  the  exercise  may  be  divided  into  a  number  of  projects  assigned  to  as  many 
individuals  or  committees. 

Where  for  any  reason  it  is  not  feasible  to  have  all  the  students  perform  the  required  exercises  at 
practically  the  same  time,  individual  or  group  projects  can  be  arranged  for  demonstration  to  the  whole 
class.  Assignments  should  be  made  well  in  advance,  so  that  the  responsible  students  or  committees  may 
have  ample  time  for  preparation.  Projects  thus  presented  before  the  class  should  be  received  most 
critically.  The  students  should  be  encouraged  to  challenge  methods  and  conclusions  in  a  thoroughly 
rigorous  fashion,  not  in  the  spirit  of  captious  faultfinding,  of  quibbling,  or  of  trapping  one  another, 
but  in  the  spirit  of  intellectual  caution.  We  must  be  jealously  on  guard  against  letting  false  or  foolish 
ideas  impose  themselves  upon  us  by  means  of  solemn  ceremonial  that  calls  itself  scientific  because  it 
is  enacted  in  a  laboratory  with  apparatus. 

The  questions  offered  in  connection  with  most  of  the  exercises  are  designed,  as  stated  in  To 
the  Student,  to  stimulate  thinking.  Here  the  teacher  should  maintain  toward  the  replies  offered  the 
attitude  expressed  by  the  query,  What  makes  you  say  that  ?  rather  than  the  attitude  of  approval  or 
disapproval  as  to  their  correctness.  It  is  more  important  to  get  the  student  to  formulate  hypotheses, 
check  them,  and  modify  them  than  it  is  to  have  him  find  the  "  right  "  answer  ;  and  in  many  cases 
nobody  knows  the  true  answer,  if  there  is  one. 

In  handling  the  mass  of  materials  and  apparatus  that  are  so  essential  for  insuring  a  consistently 
objective  treatment  of  problems,  it  is  possible  to  get  the  students  to  assume  nearly  all  of  the  burden. 
Boys  and  girls  are  glad  to  assist  where  definite  tasks  and  responsibilities  are  provided.  Students  should 
be  designated  as  curators  for  the  different  classes  of  materials  —  the  collections  of  insects,  of  flowers, 
of  fossils,  and  other  materials  assembled  for  the  museum  and  laboratory.  Other  students  may  be 
assigned  to  keep  various  special  records,  such  as  weather  charts,  temperature  records,  bird  calendar, 
and  so  on.  Those  skilled  in  lettering  and  drawing  can  assist  by  making  charts  and  diagrams  to  be 
added  to  a  growing  collection  for  class  use.  Some  students  may  be  custodians  of  current  clippings, 


M249533 


pictures,  etc.  for  the  bulletin  boards,  while  others  may  take  charge  of  pamphlets,  reference  books,  and 
other  special  reading  material. 

In  planning  the  sequence  of  exercises  it  is  necessary  on  the  one  hand  to  consider  the  sequence 
in  which  the  topics  are  to  be  studied,  and  on  the  other  hand  to  guard  against  making  the  exer- 
cises mere  busy  work.  Especially  important  here  is  the  completion  of  certain  exercises  while  the 
problems  involved  are  still  problems  —  that  is,  before  the  solutions  are  supplied  by  reading  or  dis- 
cussion. In  a  few  cases  supplementary  work  and  reading  for  students  are  suggested.  Further  sug- 
gestions will  be  found  in  the  Manual  for  Teachers. 

All  the  exercises  in  this  Manual  have  been  tried  out  in  actual  school  experience.  The  authors 
are  nevertheless  deeply  indebted  for  valuable  criticisms  and  suggestions  to  Dr.  Bertha  M.  Clark  of  the 
William  Penn  High  School,  Philadelphia ;  Mr.  Paul  B.  Mann  of  the  Evander  Childs  High  School, 
New  York ;  Dr.  A.  J.  Goldfarb,  College  of  the  City  of  New  York  ;  and  Dr.  W.  H.  D.  Meier  of  the 
State  Normal  School,  Framingham,  Massachusetts,  who  have  read  the  manuscript  or  the  proof  and  have 
given  us  the  benefit  of  their  wide  experience. 

B.  C.  G. 
F.  M.  W. 


[iv] 


LIST   OF   EXERCISES 


As  each  exercise  is  completed,  write  the  date  before  the  number  on  this  list.     This  will  help  you  check  off  your  work. 


EXERCISE 

.    1.  CHANGES  OCCURRING  AROUND  us 


2.  SOME  COMMON  PHYSICAL  CHANGES 
.   3.  CHEMICAL  CHANGES 
.  4.  REVERSING  A  CHEMICAL  CHANGE 

5.  ACIDITY  AND  ALKALINITY 

6.  CHANGE  OF  HEAT  INTO  MOTION 

7.  COMPOSITION  OF  MILK 

8.  DECOMPOSITION  OF  WATER 

9.  RELATION  OF  AIR  TO  FIRE 

.  10.  REACTION  OF  FIRE  UPON  AIR 

11.  PART  OF  AIR  USED  UP  IN  FIRE 

12.  EFFECT  OF  CO2  ON  LIMEWATER 

13.  PARTS  OF  AIR  RELATED  TO  FIRE 
.  14.  INORGANIC  GROWTH 

15.  GROWTH  OF  A  CRYSTAL 
.  16.  FUNCTIONS  OF  ORGANS 

17.  THE  MICROSCOPE 
.  18.  USE  OF  THE  MICROSCOPE 
.  19.  PLANT  CELLS 
.20.  ANIMAL  CELLS 
.21.  THE  ENVIRONMENT  OF  SEEDS 
.22.  WATER  AND  SPROUTING 
.23.  AIR  AND  SPROUTING 
.24.  GASES  OF  AIR  AND  SPROUTING 

25.  PLAN  FOR  AN  EXPERIMENT 
.  26.  EFFECTS  OF  SPROUTING  ON  AIR 
.27.  SPROUTING  AND  TEMPERATURE 
.28.  SOIL  ELEMENTS  AND  GROWTH 
.29.  EMBRYO  OF  THE  SEED 
.30.  STRUCTURE  OF  A  GRAIN 
.31.  SEEDLINGS  BREAKING  GROUND 
.32.  COTYLEDONS  AND  GROWTH  OF  SEEDLINGS 
.33.  TEST  FOR  STARCH 
.34.  TEST  FOR  PROTEINS 
.35.  OIL  IN  SEEDS 
.36.  GRAVITY  AND  ROOTS 
.37.  REGION  OF  GREATEST  GROWTH 
.38.  LIGHT  AND  GROWTH  OF  PLANTS 


EXERCISE 

39.  DIFFUSION  OF  GASES 

40.  DIFFUSION  OF  LIQUIDS 

41.  ABSORPTION  BY  CELLS 

42.  ROOT  HAIRS 

43.  FLESHY  ROOTS 

44.  ROOT  PRESSURE 

45.  TYPES  OF  ROOTS 

.  46.  AIR  AND  STARCH-MAKING 

47.  LIGHT  AND  STARCH-MAKING 

48.  CHLOROPHYL  AND  STARCH-MAKING 

49.  PLAN  FOR  AN  EXPERIMENT 

50.  GAS  EXCHANGE  IN  STARCH-MAKING 

51.  LEAF  AS  A  FACTORY 

52.  WHAT  is  AN  EXPERIMENT? 

53.  TRANSPIRATION 

54.  STRUCTURE  OF  LEAF 

55.  TRANSPIRATION  PULL 

56.  CHEMICAL  CHANGES  IN  DIGESTION 

57.  PHYSICAL  CHANGES  IN  STARCH-DIGESTION 

_58.  DIGESTION  OF  PROTEINS 
59.  DIGESTION  IN  MAN 

_  60.  THE  TEETH 

61.  FOOD  VALUES 

62.  FOOD  ECONOMY 

63.  BREATHING  IN  INSECTS 

64.  BREATHING  IN  FROG 

_65.  BREATHING  IN  FISH 

66.  COMPARATIVE  STUDY  OF  BREATHING 

67.  EXERCISE  AND  BREATHING 

68.  EVAPORATION  AND  TEMPERATURE 

69.  EVAPORATION  AND  MOISTURE 

70.  DUSTY  TRADES 

71.  STRUCTURE  OF  STEMS 

72.  MONOCOT  AND  DlCOT  PLANTS 

73.  FOOD  DUCTS  IN  BARK 

74.  CAPILLARITY 

75.  STRUCTURES  OF  THE  BLOOD 

_  76.  CLOTTING  OF  BLOOD 


[v] 


LIST    OF    EXERCISES  (Continued] 


EXERCISE 

.    77.  BLOOD  AND  GAS  EXCHANGE 


EXERCISE 

_112.  TEMPERATURE  AND  DEVELOPMENT 


.   78.  CHANGES  IN  COMPOSITION  OF  BLOOD 

.   79.  EXERCISE  AND  THE  PULSE 

.   80.  EXCRETION 

.   81.  EXCRETION  IN  ROOTS 

82.  THE  KIDNEY 
.   83.  THE  SKIN 

.   84.  TYPES  OF  EXCRETORY  ORGANS 
.   85.  PLAN  FOR  AN  EXPERIMENT 
.    86.  CONTROL  OF  THE  REFLEXES  • 

87.  BRAINLESS  ACTS 
.  88.  THE  SENSE  OF  TOUCH 

89.  FEELING  HOT  AND  COLD 

90.  THE  SENSE  OF  TASTE 

91.  DETECTING  FLAVORS 

.   92.  NEAR  SIGHT  AND  FAR  SIGHT 

93.  FEELING  LIGHT  WITHOUT  EYES 
.   94.  THE  EARS 

95.  ACUTENESS  OF  HEARING 

96.  KEEPING  A  BALANCE 
.   97.  INHIBITION 

.   98.  COMMON  LIFE  PROCESSES 

99.  NUTRITION  OF  CELL  AND  OF  ORGANISM 
.100.  RESPIRATION  OF  CELL  AND  OF  ORGANISM 
.101.  EXCRETION  OF  CELL  AND  OF  ORGANISM 
102.  COMPARATIVE  STUDY  OF  NUTRITION 
.  103.  COMPARATIVE  STUDY  OF  RESPIRATION 
.  104.  COMPARATIVE  STUDY  OF  EXCRETION 

105.  LOCOMOTION:  ANALOGIES  AND  HOMOLO- 

GIES 

106.  REACTIONS  TO  DISTURBANCE 
.  107.  FOOD-GETTING  AND  EATING 

108.  RELATION  OF  VOLUME  AND  AREA 

109.  REGENERATION 
.  110.  SEGMENTATION 

.111.  MOSQUITO,  LIFE' HISTORY 


113.  SPORE  DISTRIBUTION 

114.  SPIROGYRA  CONJUGATION 

115.  GERMINATION  OF  SPORES 

116.  THE  FLOWER 

117.  FLOWER  STUDIES 

118.  THE  POLLEN  TUBE 

.  119.  WIND  POLLENATION 
.  120.  INSECT  POLLENATION 
.121.  THE  FRUIT 
122.  DISTRIBUTION  OF  SEED 
.  123.  LIFE  HISTORY  OF  Moss 

124.  LIFE  HISTORY  OF  FERN 

125.  SPOROPHYTE  AND  GAMETOPHYTE 
.  126.  ALTERNATION  OF  GENERATIONS 

127.  PARENTAL  CARE 
.  128.  RELATION  OF  LIGHT  TO  GROWTH 

129.  SEASONAL  CHANGES 

130.  STRUGGLE  AND  SURVIVAL 

131.  CHANGES  IN  PIGMENTATION 

132.  PROTECTIVE  MOVEMENTS 

133.  HOMOLOGY  :  PROTECTIVE  ORGANS 

134.  PROTECTIVE  ACTIVITIES 

135.  FALL  OF  LEAVES 

136.  THE  FOREST  FLOOR 

137.  MOUTH  WASHES 

138.  ECONOMIC  MICROORGANISMS 

139.  FLIES  AS  DISTRIBUTORS  OF  GERMS 

140.  FLY  SURVEY 

141.  MOSQUITO  SURVEY 
.  142.  ECONOMIC  INSECTS 

143.  BIRDS 
.  144.  VARIATION 

145.  RATIO  OF  DOMINANTS  AND    RECESSIVES 
IN  HYBRIDS 


[vi] 


EXERCISES  IN  ELEMENTARY  BIOLOGY 


EXERCISE  1 

Our  world  is  made  up  of  things  that  are  constantly  changing.  Both  living  and  non-living  things 
change  from  day  to  day,  from  season  to  season. 

Problem.    What. are  some  of  the  changes  occurring  in  the  world  about  us? 

What  to  use  and  what  to  do.  Using  the  following  blanks,  in  each  column  describe  five  changes  (in 
addition  to  the  example  printed)  that  happen  to  the  kind  of  things  named  at  the  head  of  the  column. 


WEATHER 

PLANTS 

HUMAN  BEINGS  AND  OTHER 

ANIMALS 

NON-LIVING  OBJECTS 

The    air    becomes    warmer 
between  sunrise  and  noon 

Buds  on  a  tree  open 

A  sick  person  gets  well 

The  water  on  a  pond  changes 
from  liquid  to  solid 

1. 

2. 

3. 

4. 

5. 

Questions  to  think  about.     1.   What  kinds  of  changes  in  the  world  do  you  find  most  interesting? 
2.   What  kinds  of  changes  in  the  world  would  you  consider  most  important  ? 

NOTE.  In  some  of  the  changes  (for  example,  melting  ice  or  dissolving  sugar)  the  matter  takes  on  new  appearances  or 
qualities,  but  the  substance  remains  the  same.  Such  a  change  is  called  a.  physical  change.  In  other  changes,  certain  of  the 
substances  in  the  object  seem  to  disappear  entirely  and  new  materials  to  make  their  appearance,  as  in  a  flame  or  in  frying 
eggs.  Changes  of  this  kind  are  chemical  changes. 


[1] 


EXERCISE  2 

• 

Problem.  What  happens  in  some  common  physical  changes  (for  example,  pulverizing,  dissolving, 
melting,  evaporating)  ? 

What  to  use.  1 .  Any  substance  that  you  know  you  can  pulverize ;  any  that  you  know  you  can  dis- 
solve ;  any  that  you  know  you  can  melt ;  any  that  you  know  you  can  evaporate. 

2.  Any  additional  things,  material,  etc.  that  you  need  in  order  to  bring  these  changes  about. 

What  to  do.    1.  Pulverize  a  substance.  ^ 

2.  Dissolve  a  substance. 

3.  Melt  a  substance. 

4.  Evaporate  a  substance. 

Record.    Make  entries  in  proper  spaces  of  this  table. 


PULVERIZE 

DISSOLVE 

MELT 

EVAPORATE 

What     material 

was  used? 

What  was  done  to 

produce  result  ? 

How  does  the  stuff 
after  change  differ 
from  its  condition 
before  change  ? 

Question  to  think  about.     In  what  way  are  all  these  changes  alike  ? 


[2] 


EXERCISE  3 

When  a  substance  is  acted  upon  in  such  a  way  that  the  particles  of  which  it  is  made  are  com- 
pletely rearranged,  a  chemical  change  is  produced.  We  cannot  always  recognize  a  chemical  change  at 
once,  but  certain  appearances  usually  indicate  such 
a  change.  Any  one  substance  may  undergo  many 
different  chemical  changes,  just  as  any  one  sub- 
stance or  object  may  undergo  many  physical  changes. 

Problem.  To  show  some  of  the  differept  chemical 
changes  that  a  single  substance  may  undergo. 

What  to  use.  Sodium  carbonate  (washing  soda) 
solution;  water;  hydrochloric  acid  (dilute  10%); 
barium  chlorid ;  phenolphthalein  ;  5  test  tubes  and 
rack ;  I  beaker. 

What  to  do.    Have  about  I  inch  of  the  solution 

indicated  in  the  different  tubes.  Pour  solution  from  the  beaker  into  the  test  tubes,  drop  by  drop. 
Note  what  happens  immediately  after  the  addition  of  sodium  carbonate  to  the  solution  in  each  tube. 
After  a  few  minutes  shake  the  contents  of  each  tube  gently  and  note  results. 

Record.    Describe  the  results  of  adding  sodium  carbonate  to  each  tube. 


Questions.    Which  of  the  changes  you   have  described   would  you  consider  physical   and  which 
chemical  ?    Why  ? 


NOTE  I.    The  alteration  that  is  brought  about  by  the  action  of  one  thing  or  substance  upon  another  is  called  the 
reaction. 

NOTE  2.    The  discharge  of  bubbles  of  gas  from  a  solution  is  called  effervescence. 

NOTE  3.    The  production  of  solid  particles  in  a  solution  is  called  precipitation,  which  means  "  throwing  down.." 

[-3] 


EXERCISE  4 

Just  as  we  can  reverse  the  change  from  ice  to-  liquid  water  or  from  fluid  to  solid  water,  we  can 
reverse  a  chemical  change  in  some  cases,  but  not  in  all.  A  boiled  egg  cannot  be  made  raw  again  ;  a 
piece  of  charcoal  cannot  be  worked  up  into  wood ;  dried  oil  paint  cannot  be  turned  back  into 
fresh  paint. 

Problem.    How  may  I  show  a  reversible  chemical  reaction  ? 

What  to  use.  The  colored  phenolphthalein  solution  of  the  last  experiment ;  10  per  cent  hydrochloric 
acid ;  the  beaker  of  washing  soda ;  some  litmus  solution  or  litmus  paper ;  test  tubes ;  rack. 

What  to  do.  Add  hydrochloric  acid,  drop  by  drop,  to  colored  phenolphthalein  solution,  counting 
the  drops  carefully.  Shake  tube  gently  after  the  addition  of  each  drop.  Note  when  color  disappears. 
Then  add,  drop  by  drop,  counting  each  drop,  sodium  carbonate ;  again,  hydrochloric  acid ;  again,  sodium 
carbonate. 

Record.  Tell  what  happens  when  the  measured  amount  (that  is,  number  of  drops  counted)  of  the 
substance  used  in  the  experiment  has  been  added  to  the  solution  in  the  test  tube. 

NOTE  i.  The  hydrochloric-tf^zV/,  or  sour,  solution  and  the  carbonate,  or  alkaline,  solution  counteract  or  neutralize  one 
another.  A  given  amount  of  acid  substance  will  neutralize  a  certain  quantity  of  alkaline  substance,  and  vice  .versa.  The 
quantity  of  a  solution  required  to  neutralize  another  depends  upon  the  relative  concentration  of  acid  and  alkali. 

NOTE  2.  Phenolphthalein  is  colorless  in  a  neutral  or  acid  solution,  but  it  turns  red  in  an  alkaline  solution.  Substances 
that  react  differently  in  two  kinds  of  solution  may  thus  be  used  as  "  indicators." 

NOTE  3.  Litmus  solution,  made  from  a  vegetable  dye,  or  litmus  paper,  which  is  made  by  saturating  paper  with  the 
dye,  is  a  common  indicator  used  in  chemical  and  biological  laboratories. 

Repeat  the  above  experiment,  using  litmus  solution  or  litmus  paper  in  place  of  phenolphthalein. 
Record  results. 


[4] 


EXERCISE  5 

Using  small  pieces  of  litmus  paper,  test  many  different  articles  at  home  and  fill  out  following  table 


NAMES  OF  SUBSTANCES  THAT  ACTED  ON  LITMUS  PAPER 
JUST  AS  DID  THE  ACID  IN  THE  PREVIOUS  EXPERIMENT: 


NAMES  OF  SUBSTANCES  THAT  ACTED  ON  LITMUS  PAPER 
AS  DID  THE  SODIUM  CARBONATE: 


ACID  SUBSTANCES 


ALKALINE  SUBSTANCES 


Questions.    What  use  might  be  made  of  an  acid-alkali  indicator  by  (a)  a  doctor  ?    (b)  a  nurse  ? 
(c]  a  housekeeper  ? 


[5] 


EXERCISE  6 


Whenever  a  change  takes  place,  there  is  not  only  a  rearrangement  of  matter,  but  there  is  also  a 
change  in  what  we  call  "  energy."   For  example,  when  two  solids  (matter)  are  moved  against  each  other, 
their  motion  (energy)  is  changed  into  heat  (energy) ;  when  two  solids  (matter)  are  struck 
against  each  other,  their  motion  (energy)  is  changed  into  sound  waves  (energy). 
Problem.     Can  heat  be  changed  to  motion  ? 

What  to  use.    A  flask  of  colored  water,  closed  with  a  one-holed  rubber  stopper; 
a  long  piece  of  glass  tubing  connected  as  shown  in  diagram  ;  a  source  of  heat. 
What  to  do.     Apply  heat  and  note  its  effect  upon  the  water. 
Record.     Describe  changes  that  take  place  : 


WHAT  WAS  DONE 


How  MATTER  CHANGED 


ENERGY  CHANGES 


Questions.    1.  Is  there  really  more  liquid  or  less  liquid  than  there  was  before  heating? 
2.  What  do  you  suppose  happened  to  the  liquid  to  make  it  seem  of  a  different  quantity  ? 
Home  exercise.    Make  a  list  of  six  ordinary  events  or  actions  and  tell  what  change  or  changes  took 
place  in  the  matter  and  what  changes  took  place  in  the  energy. 


HAPPENING 

How  MATTER  CHANGED 

ENERGY  CHANGE 

Example 

Breathing  out  against  vocal  cords 

Cords  vibrate  and  emit  sound 

Muscular  contractions  changed 
into  sound 

1 

2 

3 

4 

5 

t 

6 

[6] 


EXERCISE  7 

Some  of  the  substances  with  which  we  are  acquainted  seem  to  be  exactly  the  same  in  all  parts  — 
for  example,  glass,  water,  iron.  Others  we  can  see  are  made  up  of  different  kinds  of  particles  —  for 
example,  streaks  in  marble,  wood,  ink. 

Problem.     What  are  some  of  the  parts  that  make  up  milk  ? 

What  to  use.  For  the  entire  class,  quart  bottle  of  milk ;  pipette ; 
evaporating  dish  ;  water  bath  ;  crucible  ;  support ;  flame.  For  each 
pupil,  two  test  tubes  and  rack ;  funnel ;  piece  of  filter  paper ; 
acetic  acid. 

What  to  do.  Allow  the  milk  to  stand  overnight,  and  remove 
the  cream  by  pouring  off  or  by  the  use  of  a  pipette.  The  residual 
milk  (skimmed)  is  then  distributed  to  members  of  class,  each  taking 
about  two  tablespoonfuls,  or  milk  enough  to  fill  test  tube  one  third 
full.  Now  add  acetic  acid  to  the  milk,  drop  by  drop,  until  a  precip- 
itate is  formed.  Separate  the  solid  substance  (curd)  from  the  liquid 
whey  by  pouring  into  a  filter  paper  supported  by  a  funnel. 

NOTE  i.  The  curd  is  made  up  largely  of  a  substance  called  casein.  This  is 
held  in  solution  by  the  alkali  naturally  present  in  the  milk.  In  an  acid  solution 
casein  precipitates  out  as  curd. 

The  teacher  will  collect  all  the  whey  and  evaporate  to  dryness  —Whey 

over  a  water  bath  or  in  a  double  boiler. 

When  all  water  has  been  driven  off,  assemble  the  solid  material 

(it  consists  of  sugar,  milk  albumen,  and  other  substances)  in  a  crucible  and  treat  the  material  with  a 
flame  until  nothing  is  left  that  will  burn. 

NOTE  2.   The  part  remaining  after  burning  is  called  ash  or,  sometimes,  mineral  matter. 

Record.  Make  an  outline  of  the  substances  that  make  up  milk.  Opposite  each  item  tell  how  each 
is  separated  from  other  constituents. 


Questions.    1.  Why  does  a  housekeeper  add  baking  soda  to  milk  when  it  begins  to  turn? 
2.   Could  milk  be  used  to  demonstrate  reversible  chemical  action  ? 


[7] 


—-Rubber-covered  wire 


EXERCISE  8 

Although  water  seems  to  be  a  simple  substance,  it  has  been  found  to  be  made  up  of  still  simpler 
substances. 

Problem.     How  can  we  show  that  water  is  made  up  of  simpler  substances  ? 

What  to  use.    Have  the  teacher  borrow 

•.—TO  socket  or  batteries  _      T-,  „„./..,,       a  eudiometer,  or  make  one  as  shown  in  the 

diagram.  A  direct  current  from  a  general 
circuit,  from  a  storage  battery,  or  from  four 
dry  cells  ;  water  ;  sulfuric  acid  ;  matches  ; 
splints. 

What  to  do.  Set  up  the  eudiometer  or 
the  piece  of  apparatus  shown.  Over  the 
ends  of  the  wires  have  two  inverted  tubes 
full  of  water  containing  a  small  amount 
of  acid.1  Turn  on  the  current  or  complete 
the  circuit  until  one  tube  is  full  of  gas. 
Note  the  changes  that  take  place  in  each 

tube.     Remove  and  invert  each  tube  and  treat  with  a  burning  match,   then   with  a  glowing  splint. 
Record.     Describe  what  happened  after  closing  the  circuit.     If  dry  cells  are  used,  decide  whether 
more  gas  is  given  off  at  the  carbon  (+)  or  at  the  zinc  (— )  pole  of  the  battery.    If  a  storage  battery  is 
used,  note  whether  more  is  given  off  at  the  +  or  at  the  —  pole. 


Questions.    1.  In  what  ways  are  the  two  gases  alike? 

2.  (a)  Which  gas  burns  ?    (b)  What  is  formed  by  the  burning  ? 

3.  How  can  you  recognize  the  other  gas  ? 

NOTE  i .  Water  is  broken  down  into  two  parts.  The  one  of  which  the  volume  is  larger  is  called  hydrogen.  The  other 
is  called  oxygen. 

NOTE  2.  Water,  up  to  the  present  time,  has  never  been  divided  into  simpler  parts  than  oxygen  and  hydrogen.  We 
cannot  break  up  oxygen  into  anything  simpler  than  oxygen,  nor  hydrogen  into  anything  simpler  than  hydrogen.  A  sub- 
stance such  as  oxygen  or  hydrogen,  gold,  silver,  chlorin,  which  we  have  not  been  able  to  break  up  into  simpler  kinds  of 
matter,  is  called  an  element.  A  chemical  combination  of  two  or  more  elements  is  called  a  compound. 


1  Pure  water  will  not  conduct  the  electric  current;  but  with  acids  or  some  other  substances  dissolved  in  it,  water  is  a 
conductor  of  electricity. 

[8] 


EXERCISE  8  (Continued) 

4.  What  are  some  of  the  compounds  you  have  studied  so  far  ? 

NOTE  3.  By  burning  some  hydrogen  in  air  we  can  easily  show  that  hydrogen  com- 
bines with  oxygen  to  form  water.  Pour  dilute  hydrochloric  acid  into  a  flask  containing 
some  small  pieces  of  zinc  covered  with  water.  After  all  the  air  is  out  of  the  flask  bring 
a  lighted  match  to  the  nozzle,  and  then  hold  a  clean,  dry  bottle  or  test  tube  over  the  flame. 

CAUTION.  If  a  flame  is  brought  near  the  gas  outlet  while  there  is  still 
air  in  the  apparatus,  there  is  danger  of  a  serious  explosion. 


5.  What  proportions  do  you  suppose  you  would  have  to  use  if  you  were  to  combine  volumes  of 
hydrogen  and  oxygen  for  producing  water  ? 

TJ 

6.  The  chemist  uses  a  shorthand  way  of  writing  water :  TT  ^>  O,  or  H2O.     Give  whatever  reasons 
you  can  think  of  for  the  use  of  either  or  both  of  these  methods  of  representing  water. 


EXERCISE  9 

In  order  to  understand  living  things  we  ought  to  know  a  great  deal  about  burning.    We  all  know 
that  air  has  something  to  do  with  burning. 

Problem.    How  is  air  related  to  fire  ? 
What  to  use.    Lighted  candle  for  fire  ;  jar ;  glass  plate. 
What  to  do.    After  making  certain  that  the  candle  will  burn  in  air,  cut  off 
the  supply  of  air  by  inverting  the  jar  over  the  lighted  candle. 

Record.    Tell  in  detail  what  you  saw  happen  to  the  candle  and  to  the  jar. 
Conclusion.   What  do  the  results  show  about  the  relation  between  air  and  fire  ? 


Questions.    1.  How  can  you  tell  that  it  was  not  the  glass  of  the  jar  that  produced  the  result? 
2.  How  can  you  tell  that  the  flame  was  not  poisoned  by  gases  given  off  by  the  fire  ? 


[10] 


EXERCISE  10 

Problem.  Does  fire  use  up  some  part  of  the  air  or  does  it  produce  new 
gases  ? 

What  to  use.  A  tall  cylinder  to  inclose  air ;  a  basin  of  water  to  a'ct  as 
a  seal  for  the  air ;  cork  float  holding  candle  on  water. 

What  to  do.  Light  candle,  float  on  water,  invert  jar  and  carefully  place 
over  candle  and  float. 

Record.    Note  all  the  changes  that  take  place. 


Questions.    1.  Is  the  same  proportion  of  the  air  used  up  in  every  fire? 

2.  Is  the  remaining  air  different  from  fresh  air  ? 

3.  From  what  happened,  can  you  tell  just  what  part  the  air  took  in  the  burning? 


°lug  of  cotton 


Pieces  of-. 
Matches 


EXERCISE  11 

Problem.  What  becomes  of  the  substance  taken  from 
the  air  when  something  burns? 

What  to  use.  Piece  of  magnesium  ribbon  8  inches 
long ;  scales  ;  weights  ;  funnel ;  match  ;  cotton  plug. 

What  to  do.  Carefully  balance  the  funnel  which  in- 
closes the  magnesium  ribbon.  Support  the  magnesium  on 
a  cork,  and  bend  it  so  that  it  does  not  touch  at  any  point. 
Ignite  the  free  end ;  be  careful  not  to  lose  any  of  the  ashes. 

Record.    Tell  all  the  changes  that  take  place. 


Questions.    1.  Is  total  weight  of  smoke  and  ash  greater  or  less  than  that  of  original  "  fuel "  ? 

2.  How  do  you  account  for  the  difference  ? 

3.  How  does  the  ash  or  smoke  differ  from  the  original  magnesium  ? 

4.  What  is  the  composition  of  the  white  powder? 


[12] 


EXERCISE  12 

In  Exercise  2  we  learned  that  there  are  certain  substances  (phenolphthalein  and  litmus  were  exam- 
ples given)  called  indicators  for  acids  and  alkalies ;  we  use  such  an  indicator  to  test,  or  try  out,  the 
acidity  or  alkalinity  of  a  substance.  In  the  study  of  living  things  we'  often  need  an  indicator  to  test 
the  presence  of  some  particular  substance,  and  different  indicators 
are  accordingly  used. 

In  Exercise  3  we  also  learned  that  a  given  substance  may  react 
in  a  distinct  way  with  other  substances  ;  for  example,  sodium  carbonate 
(washing  soda)  and  barium  chlorid  together  produce  a  white  precipitate. 
But  we  do  not  know  whether  sodium  carbonate  can  produce  a  pre- 
cipitate with  substances  other  than  barium  chlorid ;  nor  do  we  know 
whether  barium  chlorid  can  produce  a  precipitate  with  something  else 
besides  sodium  carbonate. 

Problem.    To  find  the  effect  of  carbon  dioxid  on  limewater. 

What  to  use.    Gas  generator  (see  figure) ;  limewater  with  container. 

What  to  do.  Prepare  some  carbon  dioxid  gas  by  means  of  apparatus  such  as  shown  in  diagram ; 
pour  dilute  hydrochloric  acid  on  marble  chips  through  the  thistle  tube.  Allow  the  gas  to  bubble 
through  the  limewater. 

Record.    Note  the  changes  that  take  place  in  the  limewater. 

NOTE  i .  Chemists  have  made  thousands  of  experiments  to  learn  the  effects  of  various  gases  on  limewater,  and  similar 
ones  to  learn  the  effects  of  carbon  dioxid  upon  various  substances.  Whereas  carbon  dioxid  will  produce  a  white  precipitate 
with  various  solutions,  it  is  the  only  gas  that  will  produce  a  precipitate  in  limewater.  We  may  therefore  be  sure  of  the 
presence  of  this  gas  when  we  see  limewater  turn  turbid,  or  milky. 


Question.    Write  out  a  method  for  determining  the  presence  or  absence  of  carbon  dioxid  gas  in 
the  breath  ;  test  for  the  presence  or  absence  of  carbon  dioxid  gas  in  illuminating  gas. 


H 


NOTE  2.   Just  as  we  used  the  symbol  H2O,  or  „  >  O,  to  represent  water,  we  denote  carbon  dioxid  by  the  shorthand 
method  of  CO2,  or  C  <  £?• 

[13] 


EXERCISE  13 

Ordinary  air  is  a  mixture  of  gases  made  up  approximately  of  the  following : 

Nitrogen about  79%,  or  |  of  volume 

Oxygen about  20%,  or  \  of  volume 

Carbon  dioxid about  ^% 

Problem.    What  is  the  relation  of  each  of  the  principal  gases  found  in  air  to  burning  ? 
What  to  use.    Wide-mouthed  bottles  for  containing  gases  ;  glass  covers  ;  splints  ;  matches  ;  nitrogen  ; 
oxygen  ;  carbon  dioxid  ;  water. 

The  nitrogen  will  be  prepared  by  the  teacher  or  a  committee  of  students  and  supplied  as  needed. 

To  prepare  carbon  dioxid,  see  Exercise  12. 

To  prepare  oxygen,  place  a  small  piece  of  sodium  peroxid1  (sold 
Z^Q  ^  under  the  trade  name  "  Oxone  ")  under  the  mouth  of  an  inverted 

/A  jfJ' *lf:  bottle  full  of  water,  or  heat  a  mixture  of  one  part  manganese  dioxid 

and  three  parts  potassium  chlorate  in  a  large  tube  connected  with  the 
gas  collector. 

What  to  do.    Plunge  a  lighted  splint  into  a  bottle  'of  air,  noting 
the  results.    Do  the  same  with   a   bottle  of  nitrogen ;    a  bottle  of 

carbon  dioxid ;    a  bottle  of  oxygen.    Repeat  in  each  case  until  you  are  sure  of  the  results.    Repeat 
with  a  glowing  splint. 

,  Record.    Describe  completely  what  happened  in  each  case.    Answer  the  question  in  Problem  as 
concisely  as  you  can. 


Questions.    1.  What  would  be  the  result  of  a  great  change  in  the  proportion  of  the  gases  in  our 
atmosphere  ? 

2.  How  does  blowing  into  a  flame  make  it  burn  more  briskly  ? 

3.  What  can  be  done  to  intensify  combustion  besides  increasing  the  air  supply  ? 


1  It  is  not  safe  to  use  pulverized  peroxid. 
[14] 


EXERCISE  14 

Growth  is  believed  by  many  people  to  be  peculiar  to  living  things,  but  a  very  similar  process  is 
sometimes  found  among  non-living  things. 

Problem.    To  show  in  non-living  things  a  process  that  resembles  growth  in  living  things. 

What  to  use.  A  vessel  (beaker  or  jar)  with  cover ;  clean  sand ;  numbers  of  different  kinds  of 
crystals,  such  as  zinc  sulfate,  ferrous  sulfate,  copper  sulfate,  chrome  alum,  etc. ;  sodium  silicate  (water 
glass),  i  part  to  10  parts  water. 

What  to  do.  Place  a  thin  layer  of  sand  on  bottom  of  beaker.  Place  on  the  sand  a  few  crystals  of 
various  sizes  ;  pour  in  diluted  water  glass  to  a  height  of  two  or  three  inches ;  cover.  Put  in  a  safe  place 
and  do  not  disturb  for  six  or  seven  days. 

Record.    Note  any  changes  that  take  place  in  the  jar. 


Questions.    1.  In  what  ways  does  the  behavior  of  the  things  in  the  jar  resemble  that  of  living  things? 
2.  In  what  ways  does  it  differ  from  that  of  living  things  ? 


[15] 


EXERCISE  15 

Problem.    To  show  growth  of  crystals. 

What  to  use.  Water ;  tumbler  or  beaker  ;  rod  ;  thread.  Select  one  of  several 
substances,  such  as  sugar,  alum,  hypo  salt,  table  salt,  copper  sulfate,  etc. 

What  to  do.  Stir  into  half  a  glass  of  warm  water  a  little  more  of  your  chemical 
substance  than  can  be  completely  dissolved.  Weight  a  thread  with  a  crystal  of  the 
substance  used  in  the  experiment,  and  suspend  in  the  solution  ;  leave  undisturbed 
for  a  few  days. 

Record.  Note  what  happens.  If  crystals  are  formed  on  the  thread,  dry,  bring 
to  school,  and  place  in  school  museum. 


Questions.    1.  In  what  ways  does  the  growth  of  a  crystal  differ  from  the  growth  of  a  baby? 

2.  In  what  ways  does  the  growth  of  a  crystal  differ  from  the  growth  of  a  plant  ? 

3.  What  other  things  grow  in  the  same  way  as  a  crystal  ? 


[16] 


EXERCISE  16 


The  work  which  any  organ  performs  or  the  way  it  behaves  in  relation  to  the  plant  or  animal  of 
which  it  is  a  part  is  called  its  functions.  Some  organs  perform  no  functions  useful  to  the  organism. 
Human  beings  make  use  of  various  parts  of  plants  and  animals.  This  use  may  or  may  not  have  anything 
to  do  with  the  function  of  the  part. 

In  the  following  tables  indicate  the  uses  to  which  we  can  put  the  ten  named  organs  of  certain 
animals  or  plants  and  the  functions  of  these  organs  in  the  life  of  the  organism. 


ANIMAL  ORGANISM 

PART  CONSIDERED 

I 

I    How  USED  BY  MAN  v 

FUNCTION  IN  ORGANISM 

Example 

Ox 

Tongue 

AZ^        ^^^ 

Grasps  his  food 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

PLANT  ORGANISM 

PART  CONSIDERED 

How  USED  BY  MAN 
L 

FUNCTION  IN  ORGANISM 

Example 

Hemlock 

Bark 

Tanning  material 

Protects  growing  layer 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

[17] 


EXERCISE  17 

The  compound  microscope  is  a  very  delicate  instrument,  embodying  a  great  deal  of  scientific  knowl- 
edge and  mechanical  skill.  It  should  be  handled  with  intelligence  and  consideration. 

Problem.    What  are  the  parts  of  the  microscope,  and  how  should  it  be  used  ? 

What  to  use.    A  compound  microscope ;  a  prepared  slide. 

What  to  do.    1.  Study  the  microscope  as  you  read  the  description  of  its  structure  below. 

2.  Study  the  specimen  on  the  prepared  slide,  following  the  directions  carefully. 

Record.  1.  On  the  left-hand  side,  label  all  the  parts  of  the  microscope  picture  with  the  names 
that  are  underlined  in  the  description.  On  the  right-hand  side,  tell  the  use,  or  function,  of  each  part 
that  has  been  labeled. 

2.  Make  a  drawing  of  the  object  studied  under  the  low  power  of  the  microscope,  as  large  as  it 
appears. 

NOTE.  I.  There  are  three  distinct  sets  of  parts  in  a  compound  microscope:  (a)  the  mechanical,  which  support  the 
other  parts  and  make  possible  their  controlled  movements ;  (b]  the  optical,  which  actually  do  the  magnifying  by  their  effect 
upon  the  rays  of  light  passing  through  them ;  and  (c)  the  illuminating,  which  direct  and  regulate  the  light  supply. 

•  2.  All  of  the  mechanical  parts  together  constitute  the  stand,  which  has  a  heavy  base,  supporting  a  leg,  or  pillar.  Pro- 
jecting horizontally  from  the  top  of  the  pillar,  parallel  with  the  base,  is  the  flat  stage,  with  a  hole  in  the  middle  for  letting 
light  through.  Above  the  stage  is  a  continuation  of  the  pillar,  and  extending  from  this  over  the  stage  is  the  arm,  which 
carries  a  vertical  tube.  Projecting  on  both  sides  of  the  arm  are  knobs  with  rough  edges.  These  are  connected  with  a  pinion 
that  makes  the  tube  go  up  or  down  when  they  are  turned.  The  knobs,  with  the  rack  and  pinion,  make  up  the  "  coarse 
adjustment,"  and  the  knobs  are  sometimes  called  the  coarse  adjustment  or  coarse-adjustment  screws.  By  turning  them  gently 
(one  at  a  time)  you  can  see  the  effect  on  the  tube.  The  coarse  adjustment  is  used  to  change  the  distance  between  the  lenses 
and  the  object  to  be  observed ;  that  is,  to  focus.  At  the  very  top  of  the  pillar  is  another  screw,  the  fine  adjustment,  which  is 
also  used  for  focusing  but  is  much  more  delicate  than  the  coarse  adjustment. 

3.  The  optical  system  consists  of  two  sets  of  lenses  in  metal  cases.   The  set  placed  at  the  lower  end  of  the  tube,  near 
the  object,  is  called  the  objective.    On  some  microscopes  there  is  a  special  attachment  at  the  base  of  the  tube  for  carrying 
two  or  more  objectives  conveniently ;  this  is  the  nosepiece.   With  the  use  of  the  nosepiece  it  is  possible  to  change  from 
one  objective  to  another  with  no  loss  of  time.   The  objective  that  is  in  line  with  the  tube  would  be  the  one  in  use.   Where 
there  are  two  or  more  objectives,  the  longer  or  longest  is  of  greater  magnifying  power.   At  the  other  end  of  the  tube,  near 
the  eye,  is  a  set  of  lenses  in  a  metal  case,  called  the  eyepiece,  or  ocular.   This  is  easily  taken  out  of  the  tube. 

4.  The  illuminating  system  consists  of  the  mirror,  hung  under  the  stage,  and  of  the  diaphragm,  inserted  in  the 
opening  of  the  stage.   The  mirror  usually  has  two  faces,  one  flat  and  one  concave.    It  can  be  turned  in  all  directions  and  is 
used  for  throwing  a  beam  of  light  from  the  window  (or  a  suitable  lamp)  up  through  the  object  resting  on  the  stage,  through 
the  objective  and  through  the  ocular,  into  the  eye.    The  diaphragm  is  .an  arrangement  for  enlarging  .or  diminishing  the 
amount  of  light  coming  through,  by  making  the  opening  larger  or  smaller. 

5.  Some  microscopes  have  a  joint  in  the  pillar,  just  below  the  stage,  permitting  the  upper  part  of-  the  stand  to  be 
tilted  into  a  more  convenient  position.    On  some  microscopes  one  or  two  clips  on  the  upper  surface  of  the  stage  hold  the 
slide  in  place. 

CAUTION.  In  lifting  or  carrying  the  microscope,  grasp  it  firmly  around  the  pillar  under  the  stage, 
unless  there  is  a  special  handle  for  grasping  above  the  stage. 

Allow  nothing  to  touch  any  of  the  optical  parts  except  specially  prepared  lens  paper  or  a  clean 
linen  handkerchief. 

Questions.    1.  In  which  direction  must  the  coarse  adjustment  be  turned  to  raise  the  tube? 

2.  In  which  direction  must  the  fine  adiustment  be  turned  to  raise  the  tube  ? 


Using  the  coarse  adjustment,  raise  or  lower  the  tube  until  the  tip  of  the  low-power  objective  is 
about  half  an  inch  above  the  stage. 

Looking  through  the  eyepiece,  turn  the  mirror  until  you  have  an  even  white  field  of  light. 

[18] 


EXERCISE  17  (Continued) 

CAUTION.  From  the  very  first  use  of  the  microscope  keep  both  eyes  open.  If  you  attend  to  what 
you  see  inside  the  microscope,  what  the  other  eye  sees  will  not  disturb  you.  Keeping  both  eyes  open 
avoids  straining  the  eyes. 

Place  the  prepared  slide  on  the  stage,  with  the  object  as  near  the  center  of  the  hole  in  the  diaphragm 
as  possible. 

Look  through  the  eyepiece  and  gently  raise  the  tube,  with  the  coarse  adjustment,  until  you  see  a 
clear  image.  By  turning  gently  back  and  forth  with  the  fine  adjustment  you  may  get  a  sharper  focus. 

After  the  object  is  in  focus  you  may  try  to  improve  the  illumination  by  gently  moving  the  mirror 
back  and  forth  in  various  directions  and  by  trying  smaller  and  larger  openings  of  the  diaphragm. 

After  making  the  drawing  get  a  view  through  the  high  power  as  follows :  while  the  object  is 
sharply  in  focus  turn  the  nosepiece  carefully  to  bring  the  other  objective  in  line  with  the  tube ;  listen 
or  feel  for  the  click  which  indicates  that  the  objective  is  centered.  Then  look  through  the  eyepiece 
and  gently  adjust  with  the  fine  adjustment. 

CAUTION.  Always  begin  focusing  upward,  and  guard  against  bringing  the  objective  in  contact  with 
the  cover  glass. 


Questions.    1.  Why  is  more  light  needed  for  study  with  the  high  power  than  for  study  with  the 
low  power  ? 

2.  Who  invented  the  microscope  ? 


[19] 


EXERCISE  18 

Problem.    What  does  looking  through  the  microscope  do  to  the  appearance  of  an  object  ? 

What  to  use.    Compound  microscope  ;  slide  ;  cover  slip  ;  piece  of  printed  paper  with  very  small  type. 

What  to  do.  Place  a  drop  of  water  on  the  slide  ;  immerse  paper  in  the  water ;  place  cover  slip  over 
paper,  focus  under  low-power  objective.  Keep  both  eyes  open ;  draw  what  you  see.  Center  dot  of  an 
"  i "  in  the  field,  using  the  low  power ;  then  turn  to  high  power ;  focus  carefully ;  draw. 

Record.  Make  an  outline  drawing  exactly  the  size  seen.  In  order  to  help  you  properly  to  gauge 
the  size  of  the  letter,  place  a  ruler  on  the  table  alongside  of  the  base  of  the  microscope.  Try  to  focus 
and  examine  the  letter  with  both  eyes  open.  Keep  comparing  the  size  of  the  field  and  the  dot  or  letter 
with  the  ruler.  After  the  drawing  is  made,  make  a  scale  by  measuring  off  the  length  of  the  letter  used 
on  the  slide.  Note  how  many  times  the  letter  seems  to  have  been  enlarged  when  viewed  through  low 
power ;  through  high  power.  Find  out  what  the  power  of  the  two  lenses  is  supposed  to  be  after  your 
calculation  is  finished  and  recorded. 


Special  exercise.    Look  up  the  history  of  the  microscope  and  report  in  class. 

Questions.    1.  What  happens  to  the  image  when  the  object  (slide)  is  moved  to  the  right? 

2.  What  does  the  lens  system  do  to  the  appearance  of  the  object  (image)  besides  enlarging  it  ? 

3.  What  are  some  important  uses  of  the  microscope  ? 

4.  What  important  social  or  economic  changes  have  resulted  from  perfection  of  the  microscope  ? 


[20] 


EXERCISE  19 

Problem.    What  do  plant  cells  look  like  when  examined  through  a  microscope  ? 

What  to  use.  Compound  microscope ;  slide  ;  cover  slip ;  water ;  onion  ;  elodea  or  nitella ;  iodine 
solution  or  methyl  blue. 

What  to  do.  First  remove  the  outer  portion  of  the  onion,  then  carefully  peel  a  bit  of  the  skin 
from  the  soft,  fresh  part.  Drop  into  a  flat  dish  containing  tincture  of  iodine  or  methyl  blue.  Place 
flat  in  a  drop  of  water  on  a  slide  ;  cover  with  cover  glass.  Examine  under  low  power  and  under 
high  magnification. 

Next  mount  a  small  leaf  of  elodea  or  nitella  (green  water  plants  used  in  aquaria).  Warm  by  hold- 
ing slide  on  hand  and  blowing  breath  upon  it.  Examine  under  low  and  under  high  magnification. 

Record.  Make  careful  outline  drawings  of  several  cells  of  the  onion  preparation  and  of  the  green 
plant  cells. 

Note  the  cell  wall  which  incloses  the  living  fluid,  called  protoplasm.  Part  of  this  living  fluid  (the  nucleus)  absorbs  dyes 
and  becomes  stained.  In  green  plant  cells  tiny  green  bodies  called  plastids  float  in  the  streaming  protoplasm.  These  green 
plastids  are  called  chloroplasts.  Identify  all  the  above  structures  and  label  the  drawings. 


Questions.    1.  By  slowly  moving  screw  of  fine  adjustment  (see  Exercise  17)  can  you  prove  that 
a  cell  has  a  third  dimension,  that  is,  thickness  as  well  as  length  and  width  ? 

2.  What  causes  the  green  color  of  leaves  ?    Can  you  tell  what  causes  the  colors  of  flowers  ? 

3.  What  is  your  definition  of  a  plant  cell  ? 

4.  Look  in  the  encyclopedia  and  write  a  paragraph  on  (a)  Robert   Hooke ;    (b}   Schleiden  and    i 
Schwann ;  (c)  the  cell  theory. 


[21] 


EXERCISE  20 

Problem.    What  do  animal  cells  look  like  when  viewed  through  the  microscope  ? 

What  to  use.  Microscope ;  slides ;  cover  slips  ;  prepared  slides  of  various  tissues,  scraping  from 
lining  of  mouth,  gills  from  clam,  or  drop  of  water  from  hay  infusion. 

What  to  do.    Examine  several  different  animal  cells,  preparing  as  in  previous  exercise. 

Record.  Make  careful  drawings  of  several  different  kinds  of  animal  cells ;  label  parts  of  cell  that 
were  noted  in  the  plant  cell. 


Questions.    1.  In  what  ways  may  cells  differ  from  each  other? 

2.  In  what  ways  do  the  animal  cells  studied  differ  from  the  plant  cells  ? 

3.  Why,  do  you  suppose,  were  plant  cells  discovered  nearly  two  hundred  years  before  animal  cells  ? 


[22] 


EXERCISE  21 

Problem.  Why  is  it  that  seeds  placed  under  certain  conditions  will  germinate  or  sprout,  whereas 
under  other  conditions  they  remain  unchanged  ? 

What  to  do.  Make  a  list  of  all  the  things,  substances,  or  conditions  'in  the  environment  (surround- 
ings) that  in  your  judgment  have  something  to  do  with  sprouting.  For  example,  you  may  think  that 
the  fence  around  a  field  or  the  color  of  the  flowerpot  has  (or  has  not)  some  relation  to  the  sprouting ; 
you  may  think  that  the  darkness  inside  a  bin  or  the  light  coming  through  a  glass  jar  containing  seeds 
is  an  important  factor. 

All  the  factors  in  the  environment  which  may  influence  germination  : 


1. 


6. 


9. 


10. 


In  the  light  of  all  that  you  know  about  the  sprouting  of  seeds,  place  a  +  after  each  item  that  you  are 
sure  is  a  necessary  factor  in  germination  ;  place  a  0  after  every  item  that  you  know  is  not  necessary ; 
and  place  a  ?  after  each  item  in  regard  to  which  you  are  in  doubt. 

Questions.  1.  How  do  you  know  that  the  first  item  you  have  marked  +  is  essential  to  the  sprouting 
of  seeds  ? 

2.  How  do  you  know  that  the  first  item  you  have  marked  0  is  not  essential  ? 

3.  Is  your  doubt  in  regard  to  any  item  marked  ?  due  to  your  lack  of  experience  or  to  conflicting 
observations  ? 

4.  What  factors  of  importance  had  you  overlooked  that  other  students  reported  ? 


[23] 


EXERCISE  22 

Problem.  What  is  the  relation  between  water  and  the  sprouting  of  seeds  ? 

What  to  use.  Any  large  seeds  (bean,  pea,  maize) ;  several  vessels  of  the  same  kind  (bottles,  tin 
cans,  cups) ;  water. 

What  to  do.  Arrange  a  series  of  five  vessels,  each  vessel  containing  a  different  quantity  of  water ; 
use  seeds  of  the  same  kind.  Such  a  series  may  be  made  by  supplying  equal  numbers  of  seeds  (ten  or 
a  dozen)  with  varying  quantities  of  water  —  for  example,  no  water  at  all ;  one  thimbleful  or  teaspoon- 
f  ul ;  two ;  four ;  etc.  The  seeds  in  the  last  vessel  of  the  series  should  be  placed  in  water  an  inch  or 
more  deep.  Set  all  together  in  a  safe  place. 

Record.   At  intervals  of  about  twenty-four  hours  record  the  condition  of  the  seeds  in  words  or  picture. 


VESSEL 

OR 

BOTTLE 

NUMBER 
AND  KINDS 
OF  SEEDS 

QUANTITY 

OF 

WATER 

OBSERVATIONS 

First  Day 

Second  Day 

Third  Day 

Fourth  Day 

Fifth  Day 

Sixth  Day 

Seventh  Day 

A 

B 

C 

D 

E 

Conclusion.    What  do  the  results  show  as  to  the  relation  between  water  and  sprouting  ? 


Questions.    1.  How  can  ycu  tell  that  it  was  not  the  air  that  made  some  seeds  sprout  faster  than 
others  ? 

2.  How  can  you  tell  that  it  was  not  the  temperature  that  made  some  seeds  sprout  faster  than 
others  ? 

3.  How  can  you  tell  that  it  was  not  the  light  that  made  some  seeds  sprout  faster  than  others  ? 

4.  Plan  an  experiment  that  would  answer  this  question. 

5.  How  can  you  tell  that  the  sprouting  was  not  merely  the  soaking  up  of  water  ? 


[24] 


EXERCISE  23 

Problem.     Has  air  anything  to  do  with  the  sprouting  of  seeds  ? 

What  to  use.  Seeds  that  have  been  soaked  overnight  (pea,  bean,  or  maize) ;  vessels  that  can  be 
sealed  air  tight ;  sand. 

What  to  do.  Place  groups  of  seeds  ready  to  sprout  in  situations  having  varying  quantities  of  air. 
This  can  be  done  by  using  vessels  of  the  same  size  and  equal  numbers  of  seeds,  displacing  air  by 
means  of  sand  (as  shown  on  left  side  of  diagram),  or  by  using  same-sized  bottles  and  varying  number 
of  seeds.  Have  experiment  tried  in  different  ways  by  parts  of  the  class. 

Place  all  bottles  in  same  place ;  make  observations  twenty-four  hours  apart. 

Record  carefully  all  changes  by  words  or  pictures. 


NUMBER  OF 
SEEDS 

QUANTITY 
OF  AIR 

OBSERVATIONS 

First  Day 

Second  Day 

Third  Day 

Fourth  Day 

Fifth  Day 

Sixth  Day 

rwyyvwi 

r 

f\r\f^.r\r%f^/\ 

% 

!'•:£:.;":';.;•! 

ft 

:-V  -'•*•'.•; 

& 

;V;V..-:>; 

Conclusion.    What  has  the  amount  of  air  to  do  with  sprouting  ? 

Question.    How  can  you  tell  that  the  differences  in  result  were  not  due  to  factors  other  than  air  ? 


.   [25] 


EXERCISE  24 

From  a  previous  experiment  (Exercise  23)  we  learned  that  air  is  one  of  the  factors  necessary  for 
germination.  We  might  well  ask  ourselves  the  same  questions  concerning  sprouting  of  seeds  as  we 
did  concerning  the  flame.  Reviewing  the  make-up  of  air,  consider  the  following : 

Problem.    What  part  (or  parts)  of  the  air  is  related  to  sprouting  ? 

What  to  use.  Bottles  of  no  air,  if  an  exhaust  pump  is  available  ;  of  oxygen  ;  of  nitrogen  ;  of  carbon 
dioxid ;  soaked  seeds  (peas,  beans,  or  maize) ;  air. 

What  to  do.  Place  equal  numbers  of  seeds  in  bottles  containing  the  above  gases.  Have  one  bottle 
containing  air  as  a  control,  or  check. 

Record.    Make  careful  observation  of  results  twenty-four  hours  apart. 


CONTENTS  OF  CONTAINERS 

OBSERVATIONS 

First  Day 

Second  Day 

Third  Day 

Fourth  Day 

Fifth  Day 

Sixth  Day 

Seventh  Day 

Air  -\-                      seeds 

V 

?\ 

flfifift 

No  air  -+ 

seeds 

,jsm. 
^\ 

tPo°o0<Po 

Nitrogen 

-f-               seeds 

<Po°o°cPo 

Oxygen  - 

|-                seeds 

<?o°o°o°o 

CO-,  -\-                  .    seeds 

- 

2 

<Po°o°cPo 

Conclusions.    From,  the  results  what  can  you  tell  about  the  relation  of  nitrogen,  oxygen,  etc.  to 
sprouting  ? 


[26] 


EXERCISE  25 

Work  out  a  plan  for  determining  whether  variations  of  temperature  influence  the  sprouting  of  seeds. 

Draw  up  your  Problem. 

Tell  what  you  would  use. 

Tell  what  you  would  do. 

Tell  what  results  might  be  expected. 

Tell  what  conclusions  you  would  draw  from  each  set  of  results. 


Question.    What  practical  use  could  be  made  of  the  information  ? 


[27] 


EXERCISE  26 

Problem.    Does  the  sprouting  of  seeds  produce  any  change  in  the  surrounding  air  ? 

What  to  use.  Two  flasks  or  bottles ;  seeds  ;  corks  ;  vials  containing 
limevvater  ;  wire  ;  splints  ;  matches. 

What  to  do.  Place  soaked  seeds  in  each  bottle  ;  to  one  add  a  few 
drops  of  formalin  to  kill  the  seeds ;  carefully  suspend  a  vial  of  limewater 
in  each  with  a  wire  ;  cork  ;  seal. 

Record.  After  twenty-four  hours  note  what  happens  to  the  limewater ; 
shake  gently  and  observe  again.  Test  both  bottles  for  oxygen.  What 
happened  to  the  lighted  splints  ?  to  the  spark  ? 

Conclusions.  What  gas  is  increased  in  quantity  when  seeds  sprout  ? 
What  gas  is  diminished  in  quantity  ? 


Questions.    1.  What  is  the  probable  relation  between  the  changes  in  the  air  and  changes  inside 
the  seed  ? 

2.  Why  were  two  bottles  used  in  this  experiment  ? 


[28] 


EXERCISE  27 

There  are  many  different  chemical  processes  going  on  in  plants  and  animals.  Oxidation  is  not  the 
only  one,  but  it  seems  to  be  nearly  universal,  and  it  makes  available  to  living  matter  the  energy  for  its. 
various  activities. 

Problem.    Is  heat  energy  released  when  seeds  sprout? 

What  to  use.    Three  containers  ;  large  seeds,  some  soaked,  some  dry  ;  three  thermometers. 

What  to  do.  Hang  up  thermometers  and  note  whether  they  agree  as  to  temperature  recorded.  Filf 
three  bottles,  one  with  dry  seeds,  one  with  soaked  seeds,  one  with  seeds  that  have  been  soaked  in 
water  to  which  a  few  drops  of  formalin  have  been  added. 

Record.    Note  the  reading  of  the  thermometers  at  twenty-four-hour  intervals. 


CONDITION 
OF  SEEDS 

READING  OF  THERMOMETERS 

First  Day 

Second  Day 

Third  Day 

Fourth  Day 

Fifth  Day 

Sixth  Day 

Seventh  Day 

I 

i 

^ 
1 

} 

g 

1 

*s 

;;••;• 

I 

n 

1 
i 

• 

*. 

m 

1 

i 

n 

• 

Conclusions.    What  is  there  in  the  results  that  enables  us  to  answer  the  question  in  the  Problem  ? 

Questions.    1.  Under  what  conditions  do  the  seeds  change  the  temperature  most  ? 

2.  What  is  the  effect  of  the  formalin  in  this  experiment  ? 

3.  How  can  you  tell  whether  changes  in  temperature  during  sprouting  are  related  to  oxidation  ? 


[29] 


EXERCISE  28 

Eight  or  nine  elements  are  present  in  the  most  common  salts  found  in  soil.    These  elements  are 
found  combined,  two  or  three  being  present  in  most  of  the  salts.    Thus,  sodium  chlorid  (common  salt) 
contains  sodium  and  chlorine ;   potassium  nitrate  contains  potassium,  nitrogen,  and 
oxygen ;  and  so  on.    We  saw  that  seeds  can  sprout  without  depending  upon  soil ; 
yet  something  in  the  soil  is  essential  to  the  growth  of  plants. 

Problem.  Which  of  the  substances  in  the  soil  are  necessary  for  the  continued 
growth  of  plants  ? 

What  to  use.  Young  plants  grown  from  seeds,  with  roots  carefully  washed  in 
water ;  eight  wide-mouthed  bottles  with  corks ;  distilled  water ;  chemicals  required 
for  a  nutritive  solution  (p.  24  of  Teachers'  Manual). 

What  to  do.    Prepare  a  nutrient  solution  containing  all  the  salts  given  in  the 
formula.    Prepare  another  solution  from  which  one  of  the  salts  is  omitted  ;  one  from 
which  the  second  salt  is  omitted ;  and  so  on.    Observe  growth  and  other  changes  from  day  to  day. 
Record.    Enter  the  results  in  the  proper  spaces  of  the  table  on  the  next  page. 
Questions.    1.  Which  salt  or  salts  would  seem  to  affect  growth  ? 
2.  What  other  changes  are  brought  about  by  the  absence  or  presence  of  particular  substances  ? 


[30] 


EXERCISE  28  (Continued) 


BOTTLE 
NUMBER 

GROWING-MEDIUM 

FIRST  DAY 

SECOND  DAY 

THIRD  DAY 

FOURTH  DAY 

FIFTH  DAY 

1 

Distilled  water 

2 

Containing  all  n  u- 
trients 

3 

Lacking    potas- 
sium nitrate 

4 

Lacking  calcium 
sulfate 

5 

Lacking  calcium 
phosphate 

6 

Lacking  magne- 
sium sulfate 

7 

Lacking  sodium 
chlorid 

8 

Lacking  iron 

[31] 


EXERCISE  29 

Problem.    What  is  there  in  a  seed  that  becomes  a  living  plant  ? 

What  to  use.  Different  large  seeds  (for  example,  beans,  peas,  peanuts,  cotton  seeds,  castor  seeds, 
horse-chestnuts),  some  dry,  some  soaked l  for  twenty-four  hours ;  magnifying  glass. 

What  to  do.  Examine  outside  of  seed  and  note  size,  shape,  and  position  of  scar  showing  where 
the  seed  was  attached  to  the  fruit.  This  is  the  hilum.  Look  for  a  tiny  opening  through  the  waterproof 
'coats  (testa),  called  the  micropyle.  Examine  any  other  surface  peculiarities  or  structures. 

Carefully  remove  the  seed  coats  of  two  different  seeds.  Notice  the  two  halves  of  the  seed  —  the 
fleshy  seed  leaves  called  the  cotyledons.  These  are  joined  to  a  pointed  structure  called  the  hypocotyl, 
part  of  which  grows  into  the  ground  and  becomes  the  root  and  part  of  which  becomes  the  stem.  Note 
the  first  bud,  usually  lying  between  the  cotyledons  and  attached  to  both  of  them  at  the  base.  This  is 
called  the  plumule,  or  epicotyl. 

NOTE.  All  the  structures  inside  the  coat,  or  testa,  of  most  of  the  seeds  together  make  up  the  embryo,  or  young  plant. 
Each  part  of  the  embryo  corresponds  to  one  of  the  main  parts  of  a  full-grown  plant. 

Record.    Fill  out  the  blanks  on  the  next  page  with  diagrams,  making  each  drawing  at  least  two 
inches  in  diameter.     Label  all  the  parts  for  which  names  are  given  in  the  study. 
Questions.    1.  In  what  way  do  the  cotyledons  resemble  ordinary  leaves  ? 

2.  In  what  ways  do  the  cotyledons  differ  from  ordinary  leaves  ? 

3.  How  would  the  hypocotyl  have  to  change  to  resemble  an  ordinary  root  ? 

4.  How  does  the  plumule  resemble  the  parts  of  a  plant  usually  found  aboveground  ? 


1  Add  a  few  drops  of  formalin  to  the  water  in  which  the  seeds  are  soaked,  to  prevent  fermentation  or  decay. 

[32] 


EXERCISE  29  (Continued) 


NAME  OF  FIRST  SEED 


NAME  OF  SECOND  SEED 


External  view  of  sur- 
face showing  hilum 


Embryo  shounng  all 
the  parts 


[33] 


EXERCISE  30 

There  are  many  kinds  of  plant  structures  besides  seeds  that  are  used  for  producing  new  individual 
plants,  and  that  are  really  different.  Pieces  of  potato  containing  eyes  are  sometimes  called  seeds,  and 
so  are  grains,  like  wheat,  barley,  corn,  etc. 

Problem.    How  does  a  grain  differ  from  a  seed  ? 

What  to  use.  Corn  grains,  some  dry  and  some  cooked  on  the  cob  (and  preserved  in  dilute 
formalin  solution)  ;  magnifying  glass ;  iodine  solution. 

What  to  do.  Examine  the  grains,  dry  and  cooked,  and  locate  (i)  the  point  of  attachment  to  the 
cob ;  (2)  the  little  spot  at  the  opposite  end  at  which  the  silk  was  attached ;  (3)  the  flat,  shield-shaped 
area  marking  the  position  of  the  embryo. 

Carefully  remove  the  coat  of  a  cooked  grain  without  injuring  any  of  the  structure  beneath.  Note 
two  rodlike  structures  appearing  just  below  the  surface  of  the  embryo.  The  one  pointing  toward  the 
cob  is  the  hypocotyl ;  the  one  pointing  toward  the  silk  is  the  plumule,  or  epicotyl.  The  rest  of  the 
embryo  is  cotyledon. 

Carefully  break  out  the  embryo  from  the  rest  of  the  grain.  Note  how  the  cotyledon  part  differs 
from  the  corresponding  part  in  the  seeds  studied. 

NOTE  I.  The  part  of  the  grain  left  after  removal  of  the  embryo  is  called  endosperm;  it  is  a  mass  of  food  which  is 
used  by  the  embryo  after  it  sprouts.  Many  kinds  of  seeds  also  have  endosperm. 

Cut  a  cooked  grain  through  from  the  embryo  side,  passing  through  the  plumule  in  some  and  through 
the  hypocotyl  in  others ;  cut  some  through  lengthwise,  splitting  down  the  face  of  the  embryo.  Place 
the  cut  grains  in  iodine  solution  for  a  few  minutes.  This  will  stain  the  grain  so  that  the  embryo  is 
distinct  from  the  endosperm. 

Examine  the  cut  surface  of  several  grains,  to  make  up  your  mind  what  the  shape  of  the  embryo  is. 

Record.  Make  diagrams  called  for  in  the  table  on  the  next  page  at  least  three  times  as  large  as  the 
original  object.  Label  in  each  drawing  all  the  structures  that  have  been  mentioned  in  the  study. 

Questions.    1.  What  structures  are  present  in  both  the  seed  and  the  grain  ? 

2.  What  structures  has  the  grain  that  are  not  present  in  the  seed  ? 

3.  What  structure  has  a  seed  that  a  grain  has  not  ? 

4.  What  serves  the  bean  or  pea  embryo  in  the  way  the  endosperm  serves  the  corn  embryo  ? 

NOTE  2.  Plants  whose  embryos  have  two  cotyledons  are  called  dicotyls  or  dicotyledonous  plants  ;  those  whose  embryos 
have  but  a  single  cotyledon  are  called  monocotyls  or  monocotyledonous  plants. 

5.  Name  six  dicotyls. 

6.  Name  six  monocotyls. 

7.  What  is  your  definition  of  a  grain  ? 


[34] 


EXERCISE  30  (Continued} 


External  views  of 
corn  grain 


Face  showing  embryo 


Side  view 


Sectional  views  of 
corn  grain 


Longitudinal  section 


Cross  section 


[35] 


EXERCISE  31 

When  the  embryo  has  suitable  conditions,  it  sprouts,  or  germinates.  The  small  plant  resulting  is 
known  as  a  seedling. 

Problem.     How  do  different  seedlings  break  through  the  ground  ? 

What  to  use.  Various  seeds  —  beans,  peas,  corn,  squash;  sand,  sawdust,  or  soil;  a  box  or  boxes 
to  hold  sand  ;  water. 

What  to  do.  Soak  four  varieties  of  seeds  in  water  overnight ;  plant  a  few  of  each  kind  in  a  box  of 
sand,  sawdust,  or  soil ;  keep  well  watered. 

Record.  Make  parallel  drawings  of  several  stages  of  growth  of  the  seedlings  showing  behavior  of 
homologous  (corresponding)  parts. 


1 

2 

3  ' 

4 

NAME  OF  SPECIES  : 

PART  OF  SEED 

BECOMES  IN  SEEDLING 

Cover 

Cotyledon(s) 

Epicotyl 

Hypocotyl 

Questions.    1.  What xhanges  take  place  in  the  cotyledons  as  the  seedlings  develop? 

2.  On  the  basis  of  the  limited  data  obtained  from  the  four  species  studied,  fill  in  the  above  table. 


[36] 


EXERCISE  32 


It  has  been  noted  that  seeds  will  start  to  grow  with  practically  no  food  from  the  outside.  All  that 
is  necessary  is  water,  air,  and  suitable  temperature.  We  have  noted  the  large  seed  leaves  in  certain 
seeds  (bean,  pea),  and  also  the  endosperm,  the  great  mass  of  food  stored  outside  the  cotyledon  in  the  corn. 

Problem.    Do  these  structures,  the  cotyledons  and  the  endosperm, 
have  anything  to  do  with  the  growth  of  the  seedling  ? 

What  to  use.  Different  kinds  of  very  young  seedlings ;  vessels  of  water. 

What  to  do.    After  the  seeds  have  germinated,  remove  varying  por- 
tions of  the  cotyledon  in  different  seedlings,  from  none  to  the  whole. 

Remove  varying  portions  of  the  endosperm,  from  none  to  the  whole. 

Return  to  bottles  or  pan  of  water  and  record  results  in  form  of  table. 


KIND  AND  CONDITION 

OBSERVATIONS 

After  First  Day 

Second  Day 

Third  Day 

Fourth  Day 

Fifth  Day 

Sixth  Day 

Seventh  Day 

Peas 
i.  Unaltered 

2.  One  cotyledon 
removed 

3.  Two  cotyledons 
removed 

4.  ^  of  one  cotyledon 
removed 

5.  |  of  one  cotyledon 
removed 

6.  \  of  two  cotyledons 
removed 

Corn 
i.  Unaltered 

2.  ^  of  endosperm 
removed 

- 

3.  ^  of  endosperm 
removed 

4.  All  of  endosperm 
removed 

Conclusion.   What  seems  to  be  the  relation  of  the  cotyledons  or  endosperm  to  the  growth  of  seedlings? 

[37] 


EXERCISE  33 

Just  as  the  chemist  has  worked  out  tests  for  carbon  dioxid  and  acids  and  alkalies,  we  have  tests  for 
many  of  the  useful  substances  in  foods  —  the  nutrients.  Among  the  nutrients  are  a  class  called  carbo- 
hydrates (in  which  we  find  starch  and  sugar),  the  proteins,  the  fats  and  oils,  and  the  mineral  matters 
found  in  the  ash  after  burning. 

Problem.    How  does  iodin  (the  solution  used  for  the  test)  affect  starch  ? 

What  to  use.    Starch  ;  iodin  solution  ;  test  tubes  ;  flame. 

What  to  do.  Place  a  drop  of  iodin  solution  on  a  piece  of  starch.  Stir  a  small  bit  of  starch  in  cold 
water  and  pour  into  boiling  water  in  a  test  tube  ;  allow  to  cool ;  add  a  drop  of  iodin  solution. 

Results.    Note  any  changes  that  take  place. 


Questions.    1.  You  have  found  out  how  iodin  affects  starch.    What  else  do  you  need  to  know  in 
order  to  be  able  to  use  iodin  as  a  test  for  starch  ? 

2.  Is  there  any  starch  in  the  cotyledon  of  a  bean  ? 

3.  Is  there  starch  in  the  endosperm  of  the  corn  ? 


[38] 


EXERCISE  34 

Protein,  a  class  of  substances  present  in  all  protoplasm,  and  in  lean  meat  and  fish,  can  be  found  by  a 
more  difficult  test.  The  teacher  should  perform  this  as  a  demonstration. 

Problem.  How  does  protein  act  when  treated  with  the  materials  used  in  the  xanthoproteic  ("yellow- 
protein  ")  test? 

What  to  use.  Protein,  such  as  white  of  egg  or  cottage  cheese  ;  test  tube  ;  a  source  of  heat ;  water  ; 
concentrated  nitric  acid  ;  ammonia. 

What  to  do.  Place  a  small  amount  of  protein  in  the  tube,  add  a  drop  of  concentrated  nitric  acid, 
rinse  with  water ;  boil ;  let  cool ;  add  several  drops  of  strong  ammonia. 

Results.  Note  color  after  addition  of  nitric  acid ;  then  again  after  addition  of  ammonia.  The 
appearance  of  these  two  colors  indicates  presence  of  protein. 

NOTE  i.    No  other  known  substances  produce  these  same  color  changes  after  treatment  with  nitric  acid  and  ammonia. 

Record.    Describe  results  and  give  your  conclusions. 


Problems  to  work  out.    (i)  Is  there  protein  in  the  cotyledons  of  the  bean  ?  (2)  in  the  endosperm  of 
the  corn  ?  (3)  in  the  cotyledon  of  the  corn  ?  Try  white  feathers,  wool,  skin  of  finger. 

NOTE  2.   Another  test  for  protein  that  is  often  convenient  is  to  burn  or  singe  a  bit  of  the  material  and  then  to  smell 
for  the  characteristic  odor  of  burnt  hair. 


Question.    How  do  you  account  for  this  same  odor  in  a  blacksmith's  shop  ? 


[39] 


EXERCISE  35 

The  grease-spot  test  is  used  to  determine  the  presence  of  oil  or  fat.  If  you  rub  your  fingers  through 
your  hair  and  press  them  to  a  sheet  of  paper,  a  translucent  spot  will  appear.  There  are  oil  glands  in  the 
scalp  which  give  off  droplets  of  the  material  that  registers  on  the  paper. 

Problem.    What  common  grains  or  seeds  contain  oil  ? 

What  to  use.  Clean  white  paper ;  various  kinds  of  grains  and  seeds  (for  example,  corn,  bean,  pea, 
oats,  peanut,  barley,  flaxseed,  squash,  cottonseed,  rye,  radish,  castor  bean) ;  small  mortar  or  other  means 
of  crushing  seeds. 

What  to  do.  Crush  or  grind  the  seeds  or  grains  separately.  Place  a  quantity  of  the  meal  on  white 
paper,  writing  name  of  seed  used  alongside.  Arrange  all  the  heaps  of  meal  in  order,  and  place  the 
paper  in  a  mild  oven  or  other  warm  place,  allowing  the  fat  which  may  be  present  to  melt  down  and  flow 
into  the  paper. 

Results  will  appear  after  the  meal  has  been  brushed  away. 

Record.  Make  a  list  of  the  materials  tested  and  indicate  opposite  each  whether  fat  (oil)  is  present 
or  absent. 


Questions.    1.  What  seeds  contain  large  quantities  of  oil  ? 

2.  Which  of  the  seeds  tested  contain  both  oil  (fat)  and  starch  ? 

3.  How  is  fat  rendered  from  beef  or  pork  ? 

4.  How  does  a  grease  spot  on  paper  differ  from  a  water  spot? 


[40] 


EXERCISE  36 

Problem.     How  does  gravity  influence  the  direction  of  growing  roots  ? 

What  to  use.    Two  small  glass  plates  (those  made  by  cleaning  negatives  will  serve  very  well)  ;  filter 
or  blotting  paper ;  radish  or  lettuce  seeds ;  water. 

What  to  do.  Thoroughly  moisten  two  or  three  sheets 
of  blotting  paper  and  cover  one  plate  with  it.  Place  several 
soaked  seeds  on  blotter  in  different  positions,  and  gently 
place  glass  plate  over  the  seeds.  It  may  be  necessary  to  put 
bits  of  match  sticks  in  the  corners  to  prevent  the  glass  from 
crushing  the  seeds. 

Record.  When  the  seeds  have  sprouted,  observe  and 
sketch  direction  of  growth  of  roots ;  after  twenty-four  hours 
observe  and  sketch  again  and  turn  plate  one  fourth  of  the 
way  around,  as  indicated.  Repeat  every  twenty-four  hours 
for  several  days. 

What  do  you  conclude  concerning  the  relation  of  gravity  to  the  direction  of  growth  of  roots  ? 


Jf-^S  Match-stick  sup  forts 

for  glass 

Moistened  filter  or 
blotting  faper 

Radish  or  flax  or 
any  small  seeds 

Glass 


- 

( 

X 

Questions.    1.  In  what  way  do  the  stems  seem  to  be  affected  ? 

2.  How  is  the  reaction  of  the  root  to  gravity  related  to  the  life  of  the  plant  ? 

3.  How  is  the  reaction  of  the  stem  to  gravity  related  to  the  life  of  the  plant? 

4.  How  can  you  distinguish  between  growing  down  and  simply  falling  ? 


[41] 


EXERCISE  37 

Problem.    Do  all  parts  of  the  stem  and  of  the  root  grow  at  the  same  rate  ? 

What  to  use.    Bean  or  pea  seedling  ;  India  ink  ;  brush  ;  container  for  growing  seedlings. 

What  to  do.  Paint  lines  of  india  ink  equal  distances  apart  on  root  and  on  shoot.  Return 
to  water  and  after  twenty-four  hours  examine  position  of  the  lines. 

Record.  Compare  later  condition  with  first.  Where  does  extension  of  growth  show  most? 
Where  least? 

Make  diagrams  to  show  what  has  happened,  and  the  basis  for  your  conclusion. 


Questions.    1.  Do  all  the  parts  of  your  body  grow  at  the  same  rate  ? 
2.  Are  the  rates  of  growth  the  same  all  the  time  ? 


[42] 


EXERCISE  38 

Problem.    Does  light  affect  the  direction  of  growth  in  a  plant  ? 

What  to  use.    A  geranium  (or  other  potted  plant) ;  a  sunny  window. 

What  to  do.  Notice  position  of  flat  surfaces  of  the  leaves  and  upper  tip  of  the  plant  in  relation  to 
the  window.  Turn  plant  about  180°  (halfway  around).  After  twenty-four  hours  note  carefully  what 
changes  there  are  in  the  position  of  the  leaves  and  of  the  tip.  Repeat  at  intervals  of  one  or  two  days, 
until  there  is  no  doubt  as  to  the  relation  between  the  light  source  and  the  growth  of  the  plant. 

Record.    Tell  what  happened  and  your  conclusions. 


Questions.    1.  Which  parts  of  the  plant  seem  to  be  most  sensitive  to  light? 

2.  Which  side  of  the  stem  grew  more  rapidly,  that  in  the  light  or  that  in  the  shade  ? 

3.  Try  to  tell  how  bending  is  brought  about  in  the  stem  of  the  plant  ? 

4.  How  are  changes  in  position  brought  about  in  the  leafstalk  ? 

5.  Do  all  plants  behave  the  same  way  with  relation  to  light? 

6.  Of  what  use  to  the  plant  is  the  reaction  of  light? 


[43] 


EXERCISE  39 

We  learned  that  air  is  a  mixture  of  several  odorless,  tasteless,  colorless  gases,  of  different  specific 
gravities.  Instead  of  forming  layers  with  the  heaviest  at  the  bottom  and  the  lightest  at  the  top,  gases 
in  contact  spread  through  each  other  in  all  directions,  or  diffuse. 

Problem.    How  readily  can  gases  spread  and  mix  (diffuse)  ? 

What  to  use.  Several  volatile  substances  with  distinct  odors  —  for  example,  carbon  bisulfid,  perfume, 
chloroform,  ether,  alcohol,  acetic  acid. 

What  to  do.  Open  a  bottle  of  one  of  the  substances  in  the  middle  of  the  room  ;  as  soon  as  pupils  in  the 
farthest  parts  of  the  room  detect  the  odor,  make  a  note  of  the  time.  Repeat  with  each  of  the  other  substances. 

Record.    Make  a  table  showing  the  time  required  for  each  of  the  gases  to  diffuse  a  given  distance. 


Questions.    1.  What  kind  of  gases  seem  to  diffuse  most  quickly? 

2.  How  does  an  electric  fan  affect  the  diffusion  of  gases  ? 

3.  What  would  be  the  practical  effect  if  the  gases  in  the  air  were  not  evenly  diffused  ? 


EXERCISE  40 

Problem.    Do  liquids  diffuse  in  the  same  way  as  gases  do  ? 

What  to  use.  Transparent  container  for  water  (jar,  beaker,  glass) ;  medi- 
cine dropper ;  red  ink  or  a  dye  such  as  eosin  solution. 

What  to  do.  Let  the  water  in  the  beaker  stand  for  twenty  minutes  to  make 
certain  that  there  are  no  movements  or  currents  in  it.  Place  a  large  drop  of 
red  ink  (eosin)  gently  in  the  middle  of  the  surface. 

Record.  Note  what  happens  to  the  pigment  placed  in  the  jar  of  water.  De- 
scribe final  result.  Make  a  diagram  to  show  by  means  of  arrows  the  direction 
followed  by  the  current  of  pigment. 


Questions.    1.  In  what  ways  does  diffusion  in  liquids  resemble  diffusion  in  gases? 
2.  In  what  way  does  diffusion  in  liquids  differ  from  diffusion  in  gases  ? 


[45] 


EXERCISE  41 

Problem.    How  does  a  cell  take  in  the  water  ? 

What  to  use.1   Test  tubes  ;  glass  tubing  ;  thread  or  small  rubber  bands  ;  celloidin  ;  solu- 
tions of  cane  sugar,  grape  sugar  (or  glucose),  salt ;  thin  starch  paste ;  white  of  egg. 

What  to  do.  Make  an  "  artificial  root  hair  "  by  pouring  celloidin  into  a  test  tube  until 
about  half  full,  then  pouring  back  into  the  bottle  slowly,  turning  the  test  tube  all  the  while, 
leaving  a  thin  film  lining.  Blow  into  the  tube  to  help  evaporate  the  ether  and  alcohol  in 
the  solution  of  celloidin ;  when  the  film  is  dry,  pour  in  a  little  water ;  gently  poke  the  edge 
of  the  dried  film  and  gently  push  it  from  the  tube,  being  careful  not  to  tear  it.  Place  a 
few  drops  of  water  between  the  film  and  the  glass  and  slowly  work  the  film  free  from 
the  test  tube.  Test  the  film  for  holes  by  blowing  into  it. 

Different  members  of  the  class  fill  their  sacs  with  different  solutions  —  boiled-starch 
solution,  dense  sugar  solution,  white  of  egg,  etc.  Gently  tie  a  glass  tube  in  the  end 
of  the  bag  to  serve  as  an  indicator  of  changes  inside  the  artificial  root  hair. 
Place  in  a  jar  of  water. 

Record.    Fill  in  the  following  table : 


NAME  OF  SOLUTION  IN  BAG 

DID  ANY  MATERIAL  DIFFUSE  OUT  OF  BAGS? 

WAS  ANY  MATERIAL  ABSORBED  INTO  BAGS  ? 

1. 

» 

2. 

3. 

4. 

Questions.    1.  Do  all  substances  tried  diffuse  through  the  membrane? 

2.  Do  all  diffuse  at  the  same  rate  ? 

3.  Do  all  substances  absorb  water  from  their  surroundings  ? 

4.  What  seems  to  determine  the  rate  of  absorption  ? 
NOTE.    Diffusion  of  substances  through  a  membrane  is  called  osmosis. 

5.  Where  do  you  know  diffusion  of  liquids  to  take  place  ? 

6.  Where  do  you  know  osmosis  to  take  place  ? 


1  Since  it  is  very  difficult  for  us  to  study  the  actual  workings  of  living  cells  directly,  we  shall  use  an  "artificial  root  hair 
the  present. 

[46] 


EXERCISE  42 

Problem.    What  is  the  structure  of  the  absorbing  part  of  a  root  ? 

What  to  use.  Flax  or  radish  seeds  ;  blue  or  green  blotting  paper ;  petri  dishes,  Syracuse  dishes,  or 
any  convenient  flat  containers;  magnifier  and  microscope.  The  pocket 'garden  used  in  Exercise  36 
will  serve  very  well  to  grow  the  seeds. 

What  to  do.    Place  seeds  on  moist  blotter  in  container ;  cover  and  leave  for  two  days. 

Examine  the  roots  of  the  seeds  (i)  with  the  unaided  eye,  (2)  with  a  lens,  and  (3)  under  the  com- 
pound microscope,  low  power. 

Record.  Make  a  large  drawing  of  what  you  see  in  each  of  the  above  cases ;  note  the  location  and 
relative  size  of  the  "  root  hairs." 


Questions.    1.  How  many  cells  are  there  in  a  root  hair? 

2.  What  is  the  relation  between  the  root  hairs  and  the  skin  cells  ? 

3.  Estimate  the  size  of  the  root  hair. 

4.  What  is  the  form  of  the  root  hair? 

5.  What  is  the  advantage  to  the  plant  of  these  outgrowths  on  the  root  ? 


[47] 


EXERCISE  43 

Problem.    What  is  the  structure  of  a  fleshy  root  ? 

What  to  use.  A  good-sized  fleshy  root  (for  example,  carrot  or  parsnip) ; 
glass ;  eosin  or  red  ink ;  water. 

What  to  do.  Place  tip  of  root  in  dye;  let  it  stand  for  twenty-four  hours, 
then -make  a  few  thin  cross  sections  and  cut  a  few  long  sections.  Find  the 
epidermis,  or  skin,  and  the  central  cylinder,  or  wood.  A  portion  between  the 
epidermis  and  central  cylinder  is  called  the  cortex,  or  bark ;  a  cylindrical  layer 
of  cells  between  cortex  and  central  cylinder  is  the  actively  growing  portion, 
the  cambium  layer.  Extending  from  the  cambium  toward  the  skin  and  toward 
the  center  are  the  medullary  rays. 

Record.  Make  a  drawing  of  the  cross  section,  two  inches  in  diameter,  and 
one  of  the  long  section ;  label  all  the  parts  named  in  the  study. 


Questions.  1.  From  specimen  studied,  along  what  paths  do  you  think  liquid  passes  upward  through 
the  roots  ? 

NOTE.  Plants  like  parsnip,  carrot,  etc.  usually  grow  a  large  root  and  a  head  of  leaves  from  the  seed  during  the  first 
season.  During  the  following  winter  the  root  remains  in  the  ground  and  the  part  aboveground  dies  away.  With  the  second 
season  a  flower  shoot  develops  rapidly  and  the  fruit  and  seeds  are  formed  at  the  expense  of  the  food  accumulated  in  the  root 
the  first  season. 

2.  Why  is  the  best  time  to  gather  fleshy  roots  for  human  food  late  in  the  fall  or  early  in  the  spring  ? 

3.  Why  should  roots  be  stored  in  cool  and  dry  places  ? 

4.  What  advantage  has  a  plant  like  the  dandelion  over  those  that  start  anew  from  seeds  every 
season  ?  • 

5.  If  microscopic  preparations  of  small  roots  such  as  Ricinus  (castor-oil  plant)  can  be  had,  make 
microscopic  study  and  compare  with  gross  structure. 


[48] 


EXERCISE  44 

The  water  taken  in  by  the  roots  of  a  plant  rises  in  the  stem  for  several  reasons. 
Three  of  these  are  (i)  root  pressure,  (2)  capillary  attraction,  and  (3)  the  lifting  force  of 
evaporation  of  leaves,  called  transpiration. 

Problem.  Can  water  be  absorbed  by  the  root  with  enough  force  to  raise  it  above 
the  earth  ? 

What  to  use.  A  potted  hydrangea  or  other  convenient  plant  with  stem  half  an  inch 
thick  at  the  base ;  rubber  tube  for  connection  ;  glass  tube ;  water. 

What  to  do.  Place  flowerpot  with  plant  in  a  tub  of  water  so  that  the  earth  is  covered. 
Cut  the  stem  under  water  to  prevent  entrance  of  air  bubbles  ;  attach  the  glass  tube  above 
the  stem  with  the  rubber  coupling.  Take  out  of  the  tub  and  support  the  glass  tube  in 
a  vertical  position.  Mark  the  level  of  water  in  the  tube  from  time  to  time. 

Record.    Describe  results  of  the  experiment  and  give  your  conclusions. 


Questions.    1.  In  what  ways  does  absorption  by  the  roots  resemble  osmosis? 

2.  Would  water  be  absorbed  more  easily  from  a  soil  that  had  much  material  in  solution  or  from 
one  that  had  very  little  material  in  solution  ?    Why  ? 


EXERCISE  45 

Problem.    To  find  roots  illustrating  principal  types. 

What  to  do.    Gather  two  or  three  roots  of  each  of  the  types  in  the  following  table  ;  find  the  name 
of  the  plant  to  which  each  belongs,  and  note  the  conditions  and  habits  of  each  plant. 

Record.   Complete  the  following  table  by  adding  sketches  and  notes  on  examples  you  have  gathered. 


KIND  OF  ROOT 


EXAMPLES 


Taproot 


Fibrous  root 


Bundled,  or 
fascicled 


Adventitious 
{growing 
from  stem) 


Climbing 


Parsnip 


-      Grass 


k 


Corn 


Questions.    1.  What  are  the  functions  of  roots? 
2.  What  use  does  man  make  of  roots  ? 


[50 


EXERCISE  46 

Plant  foods  are  built  up  in  the  leaves  by  means  of  a  kind  of  manufacturing  process.    Organic  mate- 
rials are  built  up  chemically  out  of  inorganic  compounds.    In  the  process  of  food  manufacture,  carbo- 
hydrates, of  which  sugar  and  starch  are  good  examples,  are  the  first  substances  put  together. 
R    Problem.    Is  the  presence  of  air  necessary  for  starch-making  ? 
What  to  use.    A  healthy  plant ;  some  material  to  keep  air  from  the  leaves  —  vaseline,  for  example. 
What  to  do.    Keep  the  well-moistened  plant  in  a  dark  closet  for  twenty-four  hours  ;  test  a  piece  of  a 
:af  for  starch.1   Coat  both  sides  of  a  certain  portion  of  a  leaf,  as  a  strip  down  the  center,  with  a  thick 
Kyer  of  vaseline.   Place  the  plant  in  sunlight ;  at  the  end  of  the  day,  break  off  the  leaf.  Test  for  starch. 
Record  results  and  state  conclusions. 
NOTE.    By  careful  experiments,  scientists  have  found  that  it  is  that  part  of  the  air  known  as  carbon  dioxid  which  is 
ed  by  plants  in  starch-making. 


1  To  test  a  leaf  for  starch,  boil  it  for  a  few  minutes  in  water,  then  place  for  a  few  minutes  in  a  large  test  tube  containing 
alcohol  (grain  or  wood)  until  all  the  chlorophyl,  or  leaf-green,  has  been  removed.  Immerse  in  iodine  solution.  (See  Exercise  33 
for  starch  test.)  Since  the  fumes  of  alcohol  are  inflammable,  it  is  well  to  carry  them  away  from  the  source  of  heat  by  means  of  a 
glass  tube  in  a  perforated  stopper  closing  the  test  tube. 

[51] 


EXERCISE  47 

Problem.    What  is  the  relation  of  light  to  starch-making  ? 

What  to  use.  A  growing  plant ;  an  opaque  mask  (made  of  black  paper)  ;  pins ; 
pieces  of  cork. 

What  to  do.  After  keeping  the  plant  in  a  dark  closet  for  twenty-four  hours,  mask 
a  portion  of  the  upper  surface  of  a  leaf  with  a  piece  of  the  opaque  paper,  pinning 
through  small  portions  of  cork ;  place  the  plant  so  that  the  masked  blade  receives  full 
and  direct  rays  of  sunlight  for  several  hours.  Remove  the  masked  leaf  from  the  plant ; 
test  for  starch  as  described  in  previous  exercise. 

Record.  Draw  diagrammatic,  shaded  representation  of  what  results  after  test; 
write  your  explanation  of  results. 


[52] 


EXERCISE  48 

The  green  plastids  which  we  noted  flowing  in  the  protoplasm  when  we  studied  the  plant  cells  of  the 
ilodea  (Exercise  19)  are  sometimes  absent  in  leaves  or  in  parts  of  leaves.  The  coleus  and  certain  other 
)lants  have  variegated  leaves  of  this  character. 

Problem.    Has  chlorophyl  (leaf  green)  anything  to  do  with  the  making  of  starch  ? 
What  to  use.    A  plant  having  a  variegated,  partly  green  leaf. 

What  to  do.    Make  a  diagram  of  one  leaf,  indicating  green  area ;  keep  the  plant  in  sunlight  for  a 
few  hours,  then  break  off  the  leaf ;  remove  chlorophyl  as  in  Exercise  46  ;  test  for  starch. 

Record.    Note  the  portion  of  the  leaf  that  has  built  up  starch ;  make  a  drawing  and  compare  with 
)ur  first  sketch.    Explain  the  results. 

NOTE.  The  part  that  chlorophyl  plays  in  the  process  of  starch-making  is  not  yet  certain.  In  terms  of  a  manufac- 
aring  process,  the  chlorophyl  grains  are  the  machinery  of  the  factory.  The  sunlight  activates  the  machinery  or  makes  it 
fork,  and  the  raw  materials  (made  up  of  compounds  of  the  elements  C,  O,  and  H)  are  separated  and  recombined  in  the  form 
}f  sugars  and  starches. 


Questions.    1 .  What  living  things  do  you  know  that  have  no  chlorophyl  ? 
2.  How  do  such  plants  and  animals  get  their  food  ? 


[53 


EXERCISE  49 

Make  a  plan  for  an  experiment  that  will  answer  the  question,  Is  water  essential  to  the  process 
of  starch-making  ? 

Make  a  plan  for  an  experiment  that  will  answer  the  question,  Is  carbon  dioxid  essential  to 
starch-making  ? 

After  comparing  notes  in  class,  to  select  the  most  reliable  and  the  most  workable  plan,  work  out 
the  answer  to  one  or  both  questions  experimentally  and  make  a  complete  report. 


[54] 


EXERCISE  50 

Problem.    What  gas  is  given  off  by  plants  during  starch-making  ? 

What  to  use.  A  watered  plant  such  as  geranium  or  hydrangea ;  bell  jar  with 
large  opening  ;  cork  ;  taper  ;  matches ;  piece  of  glass  for  base ;  vaseline  ;  candle. 

What  to  do.  Place  corked  jar  over  plant  and  lighted  candle.  After  flame 
has  gone  out,  prove  that  the  air  in  the  jar  will  not  support  combustion  by  tilting 
the  cork  and  thrusting  the  lighted  taper  into  the  jar.  Recork  jar ;  place  in 
sunlight  and  repeat  test  at  close  of  another  day  of  sunshine. 

Record.  Describe  results  and  explain  what  changes  were  brought  about  in 
the  air. 


Questions.    1.  When   a  flame  is   present  we  know  that  carbon  dioxid  is  one   of   the  results   of 
combustion.    What  happened  to  the  carbon  dioxid  produced  by  the  candle  ? 

2.  Of  what  value  are  parks  in  a  crowded  city  ? 

3.  When  are  plants  of  value  in  a  sleeping-room  ? 

4.  What  is  the  value  of  green  plants  in  an  aquarium  ? 


[55] 


EXERCISE  51 

From  the  result  of  the  preceding  exercises,  compare  the  process  of  starch-making  in  a  leaf  (or  other 
jreen  plant  part)  with  the  manufacturing  process  of  a  factory. 


FACTORS  IN  A  MANUFACTURING  PROCESS 


CORRESPONDING  FACTORS  IN  STARCH-MAKING 


Machines  or  tools 


Energy  for  driving  machines 


Raw  material 


Finished  product 


Waste  or  by-product 


Questions.    1.  There  is  always  water  and  carbon  dioxid  in  the  air;    why  is  not  carbohydrate  con- 
stantly being  formed  in  the  sunlight  ? 

2.  What  becomes  of  the  starch  that  has  been  made  by  a  leaf  in  the  course  of  the  day  ? 

3.  How  do  water  plants  obtain  their  needed  material  for  starch-making  ? 

4.  How  many  hours  out  of  the  twenty-four  could  a  plant  work  at  food-making  ? 


[56] 


EXERCISE  52 

Go  over  all  of  your  laboratory  notes  and  make  a  list  of  all  the  necessary  steps  in  the  experimental 
solution  of  a  problem. 

Explain  why  you  consider  each  step  necessary. 


[57] 


EXERCISE  53 

Water  absorbed  from  the  soil  by  the  roots  passes  through  tiny  tubes,  or  ducts,  in 
the  roots  and  stems  to  the  leaves,  where  a  part  is  used  in  starch-making,  while  the 
excess  passes  off  into  the  air. 

Problem.  Do  leaves  give  off  water  ? 

What  to  use.  Growing  plant ;  rubber  sheet  or  paraffin  paper ;  twine ;  bell  jar ; 
vaseline. 

What  to  do.  Tie  the  rubber  or  paper  over  the  pot  of  a  well-watered  plant ;  dry  the 
inner  surface  of  the  bell  jar  and  place  over  the  plant,  sealing  down  with  vaseline. 
After  twenty-four  hours  note  changes  that  throw  light  on  the  problem.1 

Record.    What  has  happened  to  answer  the  question  ? 


Questions.    1.  Why  does  it  usually  feel  cool  and  damp  in  a  forest? 

2.  How  do  trees  help  prevent  floods  ? 

NOTE.   The  process  of  water  removal  through  the  leaves  is  called  transpiration. 


1  The  experiment  may  be  tried  with  a  single  healthy  leaf  by  setting  up  as  in  B.  Use  a  cardboard  to  separate 
the  air  chamber  from  the  water  bottle,  and  seal  up  the  space  around  the  leafstalk  with  paraffin  or  vaseline. 

[58] 


EXERCISE  54 

Problem.    How  does  water  get  out  of  the  leaf  ? 

What  to  use.    A  compound  microscope  ;  a  coleus  or  geranium  leaf ;  slides ;  cover  glasses  ;  water. 
What  to  do.    Strip  a  small  piece  of  the  lower  epidermis  of  the  leaf,  mount  in  water  on  a  slide,  place 
a  cover  slip  over  the  preparation,  and  examine  both  through  low  and  through  high  power. 
Record.    Make  a  careful  drawing  of  what  you  see ; 1  label  all  you  can  make  out. 


Questions.    1.   Can  you  suggest  an  advantage  of  the  location  of  stomata  on  the  under  surface  of 
the  leaf  ? 

2.  Where  would  you  look  for  the  stomata  of  a  lily  pad  ? 

NOTE.    Cross  sections  of  leaves  show  enlarged  spaces  just  inside  the  stomata.  Water  evaporates  into  these  spaces  from 
the  leaf  cells,  and  the  vapor  diffuses  out  through  the  stomata. 


1  The  special  arrangement  of  cells  leaving  an  opening  in  the  skin  is  called  a  stoma,  meaning  mouth  (plural  stomata).    The 
large  cells  surrounding  the  stoma  are  called  guard  cells.    The  stomata  allow  air  to  pass  in  as  well  as  water  (vapor)  to  pass  out. 

[59] 


EXERCISE  55 


We  saw  that  through  the  actions  of  the  roots  water  is  made  to  rise  above  the  surface 
of  the  ground  (Exercise  44). 

Problem.  Can  the  transpiration  from  the  leaves  raise  water  in  a  plant  ? 

What  to  use.  Glass  tube;  water;  sealing  wax  or  paraffin;  a  living  leaf;  small  dish 
of  mercury.1 

What  to  do.  Fasten  the  stalk  of  a  vigorous  leaf  in  the  end  of  a  glass  tube  with  sealing 
wax  or  paraffin. 

Fill  the  tube  with  water  and  place  the  open  end  in  the  mercury,  avoiding  the  entrance 
of  air  bubbles. 

Watch  the  set-up  from  time  to  time  for  any  change  in  the  level  of  mercury  in  the  tube. 

CAUTION.    See  that  the  end  of  the  stalk  is  clean  and  free  from  the  sealing  material. 

Record.  Tell  what  happens  and  show  what  light  it  throws  on  the  problem  of  the  rise 
of  water  to  the  top  of  a  high  tree. 


Questions.  1.  Under  what  conditions  would  leaves  give  off  the  largest  amount 
of  water  ? 

2.  Find  out  the  specific  gravity  of  mercury  and  calculate  the  amount  of  water- 
raising  represented  by  the  change  in  the  column  of  mercury. 


1  If  mercury  is  not  to  be  had,  connect  the  apparatus  as  shown  in  the  figure.    Any  water-raising 
effect  resulting  from  the  transpiration  would  be  shown  by  the  rise  of  water  in  the  second  bottle. 

[60] 


EXERCISE  56 

Problem.    What  changes  take  place  in  a  cracker  when  it  is  chewed  in  the  mouth  ? 

What  to  use.    Soda  crackers  ;  test  tubes 1 ;  iodin  solution  ;  Fehling  solution. 

What  to  do.  Gather  some  saliva  in  a  test  tube  ;  test  part  of  it  for  starch  and  part  for  grape  sugar. 
Test  a  piece  of  dry  soda  cracker  for  starch  and  for  grape  sugar.  Chew  a  piece  of  soda  cracker  for  two 
minutes,  being  careful  not  to  swallow  any  of  it.  Place  a  small  amount  of  chewed  cracker  in  each  of  two 
test  tubes.  Test  for  starch  and  for  grape  sugar. 

Record.2 


SALIVA 

UNCHEWED  CRACKER 

CHEWED  CRACKER 

Starch 

Sugar 

Questions.    1.  What  is  the  source  of  the  sugar  found  ? 

2.  How  can  you  tell  that  it  did  not  come  from  the  saliva  ?  from  the  teeth  ? 


1  You  can  increase  the  flow  of  saliva  by  chewing  a  piece  of  paraffin. 

2  Indicate  presence  by  +  and  absence  by  0. 

[61] 


EXERCISE  57 


Problem.  What  physical  changes  result  from  the  digestion 
of  starch  ? 

What  to  use.  Four  "artificial  root  hairs"  made  as  described 
in  Exercise  4 1  ;  boiled  starch  paste,  thin  enough  to  pour  easily ; 
diastase1;  pancreatin  ;  saliva  (see  note  I,  Exercise  56);  iodin 
solution ;  Fehling  solution. 

What  to  do.    Fill  the  celloidin  membranes  with  starch  paste. 
Into  one  mix  a  small  amount  of  diastase;  into  the  second,  some 
pancreatin  ;   into  the  third,  about  a  teaspoonful  of  saliva.    Im- 
merse each  sac  in  water,  as  shown  in  diagram.    Test  the  water  surrounding  each  cell  for  starch  and 
for  reducing  sugar.    Record  results.    After  twenty-four  hours  test  again  and  record.    Then  test  contents 
of  each  sac  for  starch  and  for  sugar.    Complete  record  in  table. 
Record. 


SURROUNDING  WATER 

INSIDE  OF  CELL 

Fresh 

After  Twenty-four  Hours 

Starch 

Sugar 

Starch 

Sugar 

Starch 

Sugar 

1.   Starch  paste  only 

2.  Starch  paste  and  diastase 

3.  Starch  paste  and  pancreatin 

4.  Starch  paste  and  saliva 

Conclusions.    What  is  the  answer  to  the  problem  ? 

Questions.    1.  Can  starch  diffuse  through  a  cell  wall  ? 

2.  Can  sugar  diffuse  through  a  cell  wall  ? 

3.  What  is  the  source  of  any  sugar  found  in  this  experiment  ? 

4.  What  can  change  starch  into  sugar  ? 

5.  Will  starch  change  into  sugar  of  itself  ? 

6.  How  does  digested  starch  differ  from  undigested  starch  ? 


1  The  diastase  should  be  tested  before  used,  as  the  commercial  product  sometimes  contains  a  reducing  sugar. 

[62] 


EXERCISE  58 

Digestion  of  food  in  the  human  body  takes  place  in  (i)  the  mouth,  (2)  the  stomach,  and  (3)  the 
intestine.  In  each  of  these  spaces  there  is  at  work  a  special  digestive  fluid  :  (i)  the  saliva,  containing  the 
ferment  ptyalin  ;  (2)  the  gastric,  or  stomach,  juice,  containing  the  ferment' pepsin  ;  and  (3)  the  pancreatic 
juice,  containing  several  ferments. 

Problem.    Which  of  the  digestive  fluids  acts  upon  protein  ? 

What  to  use.  Pieces  of  egg  albumen1;  some  saliva2;  a  solution  of  pepsin  ;  a  solution  of  pancreatin  ; 
test  tubes  ;  water  ;  absorbent  cotton. 

What  to  do.  Place  in  the  test  tubes  strips  of  albumen  of  about  the  same  size.  In  one  tube  place 
water ;  in  the  second,  saliva ;  in  the  third,  pepsin  solution  ;  in  the  fourth,  pancreatin  solution.  Close 
tubes  with  cotton  plugs.  Place  all  in  a  warm  place  overnight ;  note  changes  in  the  egg  every  day  until 
one  of  the  pieces  is  definitely  eaten  away. 

Record.    Indicate  in  the  appropriate  spaces  the  amount  of  change  produced  day  by  day  in  each  tube. 


First  Day 

Second  Day 

Third  Day 

Fourth  Day 

Fifth  Day 

Protein  + 

Water 

Protein  + 
Saliva 

• 

Protein  -\- 

Pepsin 

Protein  -+- 
Pancreatin 

Questions.   1.  What  solutions  brought  about  the  digestion  of  protein  ? 

2.  Which  solution  acted  most  quickly  ? 

3.  In  what  parts  of  the  body  may  proteins  be  digested  ? 


1  From  the  white  part  of  a  hard-boiled  egg  thin  strips  are  cut  with  a  sharp  knife. 

2  See  Note,  Exercise  56. 

[63] 


EXERCISE  59 

Problem.    What  digestive  processes  take  place  in  the  human  body  ? 

A  study  of  the  different  nutrients  and  of  the  digestive  system  in  man  should  leave  us  clear  as  to 
what  happens  normally  to  every  part  of  our  food  after  it  is  eaten.  Make  a  diagram  at  least  five  inches 
long,  showing  all  the  important  organs  of  the  digestive  system.  On  the  left  side  of  the  diagram  make 
a  list  of  the  organs  and  draw  lines  to  indicate  the  corresponding  parts  of  your  diagram.  On  the  right- 
hand  side  make  a  list  of  the  food  substances  that  are  digested  in  each  of  the  organs  shown,  and  connect 
with  a  line  to  the  corresponding  part  of  the  diagram. 


Question.    How  is  it  possible  for  a  person  to  continue  to  live  after  the  stomach  has  been  removed  ? 


[64] 


EXERCISE  60 


I  Problem.    To  find  the  condition  of  my  own  teeth. 
What  to  use.    Small  hand  mirror  to  go  into  mouth  ;  larger  mirror  ;  diagram  of  complete  set  of  teeth. 
What  to  do.    Examine  all  your  teeth  with  the  two  mirrors;  indicate,  on  diagram  all  the  incisors, 
canines,  premolars,  and  molars. 

Record.    Locate  the  approximate  position  of  any  cavity  by  an  arrow  (— >).    If  any  of  your  teeth  are 
missing,  shade  the  corresponding  part  of  the  diagram  (•).   Mark  position  of  loose  or  broken  teeth  with  a  X. 


Questions.    1.  (a)  How  many  teeth  are  there  in  a  full  and  complete  set?  (b)  How  many  (unshaded) 
teeth  does  your  diagram  show  ?  (c}  Account  for  the  lack  of  any  teeth. 

2.  Did  your  teeth  seem  to  be  properly  cleaned  of  (a)  particles  of  food,  (&)  a  hard  deposit,  called  tartar  ? 

3.  Suggest  motion  of  toothbrush  application  that  will  (a)  remove  particles  of  food  and  (b}  clean  the 
surface  of  the  teeth. 

4.  How  can  tartar  be  removed  ? 

5.  Recommend  course  of  action  to  be  followed  as  a  result  of  the  study  and  record  made  in  this  exercise. 


[65] 


EXERCISE  61 


Problem.    What  is  the  food  value  of  the  meals  we  eat  ? 

What  to  use.  A  table  of  food  values,  such  as  Dr.  Irving  Fisher's  loo-Calorie  Portions  Table  (p.  96 
of  text)  or  Mr.  Frank  Rexford's  One-Portion  Table  (p.  98  of  text) ;  a  careful  list  of  all  the  food  eaten 
by  two  or  three  members  of  your  family  for  one  day. 

What  to  do.  Fill  in  a  table  like  the  following  for  each  member  of  the  family,  making  the  calculations 
from  the  Fisher  or  Rexford  table. 


RECORD  O 

F  FOOD  EATEN  BY       -     --                                            -                                                   ON        

OCCUPATION 

NAME  OF  FOOD 

SIZE  OF  PORTION 

WEIGHT  OF  PORTION 

CALORIES  FROM 

Proteins 

Fats 

Carbohydrates 

Breakfast 

• 

Luncheon 

Dinner 

Totals 

Record.    Have  a  committee  of  pupils  compare  on  special  sheet  or  blackboard  the  result  of  work  of 
the  class. 

Criticize  one  of  the  dietaries,  indicating  its  strong  points  and  its  weak  points. 
Show  how  it  can  be  improved. 

[66] 


EXERCISE  62 

Problem.    What  is  the  relative  economy  of  different  kinds  of  food  ? 

What  to  use.  Fisher's  table  (p.  96  of  text)  and  a  list  of  current  prices  of  foods  obtained  from  dealers. 

What  to  do.  Find  out  the  price  of  ten  different  articles  of  food.  By.  means  of  Fisher's  table  com- 
pute the  price  of  100  calories  of  each  article  and  further  calculate  the  amount  of  each  food  that  can  be 
purchased  for  10  cents.  Finally,  distribute  the  food  units  contained  in  this  amount  of  food  by  calories. 

Record.  Make  your  report  on  a  table  ruled  off  as  below ;  bring  to  class  for  comparison  with  other  students. 


ARTICLE 

PRICE  PER  UNIT 
GENERALLY  SOLD 

COST  OF  100-CAL- 
ORIE  PORTION 

QUANTITY  FOR 
10  CENTS 

CALORIES  IN  10-CENT  PORTION 

Protein 

Fats 

Carbohydrates 

Example 

Peanuts 

j  cents  per  box 
of  twenty-six 

£6:5  ::  13  :x 
x  =  2j 

2  boxes 

1.28  02. 

40 

126 

34 

1 

2 

3 

4 

5 

» 

6 

7 

8 

9 

10 

Questions.    1.  Compare  the  papers  of  the  class  and  decide  what  food  gives  the  greatest  amount  of 
protein  for  the  least  money. 

2.  What  food  contains  the  largest  amount  of  fuel  for  10  cents  ? 

3.  List  in  the  order  of  their  economy  the  foods  that  you  have  named. 

4.  Which  food  gives  nearest  to  a  balanced  meal  for  the  lowest  price  ? 


[67] 


EXERCISE  63 

Problem.    What  structures  does  an  insect  use  in  breathing? 

What  to  use.  Some  living  insect  in  a  bottle  closed  loosely  with  cotton  or  paper  (a  good-sized  grass- 
hopper or  bumblebee  will  serve) ;  some  preserved  specimens  or  some  freshly  killed  large  grasshoppers 
or  moths  ;  magnifying  glass  ;  microscope. 

What  to  do.  Watch  the  living  insect  with  lens  and  note  any  movements  of  the  posterior  part  of 
the  body,  known  as  the  abdomen.  Note  the  tiny  openings  on  the  sides  of  the  abdomen  —  the  spiracles. 

On  a  preserved  or  freshly  killed  insect  examine  a  spiracle  with  a  compound  microscope.  Using  a 
large  grasshopper  or  moth,  dissect  out  with  sharpened  needles,  under  water,  the  tubes  leading  from 
these  spiracles  —  the  tracheae.  Study  under  the  microscope. 

Record.    Make  an  outline  drawing  of  the  side  view  of  the  insect,  showing  location  of  spiracles. 

Describe  the  movements  of  the  abdomen  of  the  live  insect. 

Draw  a  sketch  of  the  tracheae  that  you  observed  in  the  dissection,  under  the  microscope. 


Questions.    1.  What  happens  to  air  in  tubes  when  the  abdomen  contracts  ?  when  it  expands  ? 
2.  What  structures  in  grasshoppers  correspond  to  our  nostrils  ?    to  our  bronchial  tubes  and  lungs  ? 
to  our  chest  walls  ?  to  our  diaphragm  ? 


[68] 


EXERCISE  64 

Problem.    How  does  the  frog  breathe  ? 

What  to  use.  A  live  specimen  in  a  battery  jar,  or  a  freshly  killed  specimen  ;  straw ;  dissecting 
needle ;  glass  tube  drawn  out  almost  to  a  point. 

What  to  do.  Locate  the  nostrils  and  observe  their  movements  during  the  breathing  process.  Note  the 
movements  of  the  floor  of  the  mouth,  under  the  jaw.  Watch  the  frog  as  he  seems  to  swallow  and  also 
watch  the  throat  and  the  nostrils  during  this  process.  Observe  the  sides  of  the  animal  and  see  if  you 
can  correlate  the  various  motions ;  that  is,  do  the  sides  puff  out  when  the  throat  puffs  out  or  when 
it  contracts  ?  • 

On  a  freshly  killed  specimen  note  by  probing  with  a  straw  where  the  nostrils  lead.  Does  this  help 
you  to  decide  why  the  throat  puffs  out  ?  At  the  rear  of  the  mouth  locate  a  raised  spot,  and  with  the 
dissecting  needle  pull  one  side  away  from  the  rest,  thus  disclosing  a  narrow  slit,  the  glottis,  in  the 
middle  of  the  elevation.  Gently  insert  the  glass  tube  in  the  glottis  and,  by  blowing,  inflate  the  lungs. 
Does  this  help  you  decide  why  the  animal's  sides  puff  out  ?  Dissect  out  the  lungs  and  the  tubes  that 
connect  them,  noting  where  the  tubes  (bronchi)  join  and  form  the  trachea  and  where  this  one  tube 
enters  the  mouth. 

Record.   Draw  a  picture  of  the  nostrils  and  the  lungs  and  tubes. 


Questions.    1.  Tell  how  air  enters  a  frog's  mouth. 

2.  How  is  air  forced  into  the  lungs  ? 

3.  How  is  air  expired  ? 

NOTE.    The  frog  has  no  diaphragm  as  have  human  beings  and  other  mammals. 

4.  What  does  the  work  of  this  structure  ? 

5.  What  would  happen  if  a  frog's  mouth  were  kept  open  indefinitely  ?    Why  ? 

6.  How  does  the  frog  breathe  when  buried  in  the  mud  in  winter  ? 


[69] 


EXERCISE  65 

Problem.    How  does  a  fish  breathe  ? 

What  to  use.  Living  fish  (goldfish,  perch,  or  bream)  in  a  battery  jar ;  carmine ;  small  pipette ; 
preserved  fish. 

What  to  do.  Observe  the  swallowing  movements  of  the  fish.  See  whether  you  can  tell  what  happens 
to  the  water  after  it  enters  the  mouth.  Take  up  a  small  quantity  of  carmine  suspended  in  water  in  the 
pipette.  Lower  the  tip  of  the  pipette  gently  below  the  surface  of  the  water  in  the  jar,  and  hold  it  until 
the  fish's  mouth  is  near  it ;  then  gently  discharge  the  carmine  into  the  water  so  that  the  fish  will  be 
likely  to  swallow  some  of  it.  (It  will  not  hurt  the  fish.)  See  whether  you  can  trace  the  course  of  the 
water  that  the  fish  swallows. 

Cut  off  the  flap  on  one  side  of  the  preserved  fish's  head.  This  flap  is  called  the  operculum.  The 
feathery  structures  under  the  operculum  are  the  gills.  Study  a  single  gill  and  find  the  bony  arch,  the 
raker,  and  the  small  subdivisions  of  the  gill  among  which  the  water  passes. 

Record.  1.  Draw  side  view  of  head  of  fish,  and  indicate  by  means  of  arrows  the  path  taken  by 
the  water  when  the  fish  breathes. 

2.  Draw  a  single  gill,  enlarged. 


Questions.    1.  Where  are  the  muscles  located  that  set  up  the  currents  of  water  for  the  fish's  breathing  ? 

2.  Why  is  it  necessary  to  change  the  water  or  to  keep  green  plants  in  an  aquarium  ? 

3.  In  what  way  does  the  breathing  of  the  fish  resemble  that  of  the  frog  ?    In  what  way  do  they  differ  ? 

4.  What  has  osmosis  to  do  with  the  breathing  of  the  fish  ? 

5.  Which  part  of  the  gill  always  faces  the  mouth  ?    Which  part  always  extends  in  the  opposite 
direction  ?    Can  you  tell  how  this  arrangement  is  important  ? 

6.  What  are  the  functions  of  each  part  of  the  gill  ? 


[70] 


EXERCISE  66 

Problem.    A  comparison  of  breathing  in  different  animals. 

What  to  use.     Laboratory  notes  on  breathing;  any  sources  of  information  about  the  breathing  of 
animals,  including  man. 

What  to  do.     Compile  information  into  the  table  below. 


HUMAN  ORGANS  CONCERNED 
IN  BREATHING 

CORRESPONDING  ORGANS  OR  PROCESSES  IN 

Paramecium 

Insect 

Fish 

Frog 

Nostrils 

• 

Bronchial  tubes  and 
trachea 

Lungs 

Diaphragm 

Process  of  inhalation 

. 

Process  of  exhalatio?i 

Questions.    1.   In  what  ways  is  breathing  alike  in  all  animals  ? 

2.  How  does  breathing  in  animals  resemble  breathing  in  plants  ? 

3.  How  does  breathing  in  animals  differ  from  breathing  in  plants  ? 


[71] 


EXERCISE  67 

Problem.    What  effect  has  moderate  exercise  on  the  rate  of  respiration  ? 

What  to  use.    Chart  for  keeping  record  of  class. 

What  to  do.  As  teacher  keeps  time  for  one  minute,  count  number  of  breaths  taken  during  the 
interval.  After  a  brisk  two-minute  drill  or  setting-up  exercise,  count  breaths  as  before  for  one  minute. 

Record  your  own  count :  Before  exercise  After  exercise  

Record.  In  the  table  below  enter  in  appropriate  spaces  the  number  of  students  who  took  12  breaths 
per  minute  before  exercising,  the  number  who  took  13  breaths,  and  so  on.  Then  record  in  the  same 
way  the  number  who  took  12  breaths  after  exercising,  the  number  who  took  13  breaths,  and  so  on.1 


BREATHS  PER  MINUTE 

12 

•13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

Before  exercise 

After  exercise 

Questions.    1 .  What  is  the  lowest  breathing  rate  in  the  class  before  exercise  ? 

2.  What  is  the  highest  breathing  rate  ? 

3.  What  is  the  average  breathing  rate  ? 

4.  What  effect  has  exercise  on  the  rate  of  breathing  ?    Can  you  tell  why  ? 

5.  Can  you  find  any  connection  between  age  and  the  rate  of  breathing  ?  between  sex  and  the  rate 
of  breathing  ?   between  stature  and  the  rate  of  breathing  ? 

6.  What  besides  exercise  makes  your  breathing  rate  vary  ? 


1  You  can  show  all  the  facts  graphically  by  drawing  a  horizontal  line  across  the  appropriate  space  for  each  student  who  took 
a  given  number  of  breaths  per  minute.  If  the  horizontal  lines  are  equal  distances  apart  (say  an  eighth  of  an  inch),  the  heights 
of  the  columns  will  correspond  to  the  number  of  students  in  each  group. 

[72] 


EXERCISE  68 

The  sweat  glands  are  constantly  bringing  perspiration  to  the  surface  of  the  skin,  where  the  water 
evaporates  immediately.  But  at  high  temperatures  the  perspiration  comes  to  the  surface  faster  than 
it  can  evaporate,  and  so  the  drops  of  fluid  become  visible.  Whenever  .anything  interferes  with  free 
perspiration,  or  with  the  evaporation  of  water  from  the  surface,  the  temperature  of  the  body  is  likely 
to  rise  and  thus  cause  more  or  less  serious  discomfort. 

Problem.     How  does  the  evaporation  from  the  surface  affect  the  temperature  ? 

What  to  use.  A  small,  thin  w-atch  glass;  ether;  alcohol* or  gasoline;  water;  a  sheet  of  stiff  paper 
or  a  fan  ;  a  thermometer. 

What  to  do.  1 .  Place  a  few  drops  of  water  on  the  table ;  in  this  set  the  watch  glass  nearly  full  of 
ether ;  under  the  edge  of  the  glass,  in  the  water,  place  the  bulb  of  the  thermometer,  after  reading  the 
temperature.  Fan  the  surface  of  the  ether  until  it  has  all  evaporated.  Remove  the  watch  glass ; 
examine  the  water  and  read  the  thermometer. 

CAUTION.    See  that  there  is  no  open  flame  about  while  working  with  ether  or  gasoline. 

2.  Place  a  few  drops  of  alcohol  or  gasoline  on  your  finger  and  move  your  hand  rapidly  through  the 
air ;  note  what  sensation  you  have  regarding  change  in  temperature. 

Record.  Describe  the  results  found  in  I  and  2.  What  do  you  conclude  as  to  the  relation  of 
evaporation  to  temperature  ? 


Questions.    1.  What  becomes  of  the  heat  that  seems  to  disappear? 

2.  How  does  fanning  help  to  keep  cool  ? 

3.  Does  a  breeze  or  fanning  cool  the  body  when  there  is  no  moisture  (perspiration)  on  the  surface  ? 
What  is  the  reason  ? 

4.  What  conditions  in  the  air  can  interfere  with  rapid  evaporation  of  the  perspiration  ? 

5.  Do  we  perspire  more  on  a  muggy  day  or  on  a  dry  day  ?    Why  ? 


[73] 


EXERCISE  69 

The  air  cells  of  the  lungs  expose  a  large  surface  to  the  air  which  is  breathed  in.    Through  the 
membranes  lining  the  air  cells  the  exchange  of  gases  takes  place  by  osmosis.    To  keep  up  this  gas 

exchange  it  is  necessary  that  the  membranes  be  kept  constantly  moist. 
Problem.    What  effect  has  the  amount  of  moisture  in  the  surround- 
ing air  upon  evaporation,  or  drying  up  ? 

What  to  use.  Filter  paper ;  two  preserving  jars  ;  water. 
What  to  do.  Soak  a  piece  of  filter  paper  in  water ;  divide  it  into 
two ;  fasten  each  piece  on  the  under  surface  of  one  of  the  jar  lids  (use 
sealing  wax  or  paraffin).  In  the  bottom  of  one  jar  place  water  to  a 
depth  of  an  inch  ;  leave  the  other  jar  dry ;  close  the  jars  with  the  lids 
from  which  the  wet  paper  is  suspended. 

Record.    What  is  the  condition  of  the  two  papers  at  the  end  of 
after  forty-eight  hours  ?    What  effect  has  the  presence  of  water  in  the  bottom  of 
What  is  the  answer  to  the  problem  ? 


twenty-four  hours  ? 

the  jar  upon  the  air  in  the  jar  ? 


Questions.    1.  Why  do  clothes  dry  more  readily  on  some  clear  days  than  on  others? 
2.  What  are  the  advantages  (or  disadvantages)  of  a  dry  atmosphere  in  warm  rooms  ? 


[74] 


EXERCISE  70 


Problem.  In  what  local  industries  are  the  workers  exposed  to  vapors,  dusts,  or  fumes,  that  are 
harmful  ? 

What  to  do.  Make  a  survey  of  the  community,  fill  out  a  blank  like  the  one  below,  and  bring  to  class 
for  comparison  with  those  of  fellow  students.  After  comparing  notes  make  as  complete  a  list  as  possible. 


NAME  OF  INDUSTRY 


NATURE  OF  THE  HAZARD- 


PRECAUTION  OR  SAFEGUARD 
EMPLOYED 


SUGGESTIONS 


Dupont  T.  N.  T.  Co. 


Working  with  a  poison 
that  is  absorbed  through 
the  skin 


Workmen  employed  in 
short  shifts  and  for  limited 
time  in  T.  N.  T.  Fre- 
quent medical  observation 
and  examination 


[75] 


EXERCISE  71 

Problem.  How  does  the  monocotyledonous  stem  compare  with  the  dicotyledonous  stem  in  gross  and 
microscopic  structure  ? 

What  to  use.  Any  good-sized  monocot  stem,  such  as  cane,  corn,  bamboo ;  a  good-sized  dicot,  such 
as  willow,  hickory,  maple ;  stained  sections  of  young  seedlings  of  corn  and  ricinus  or  other  dicot  herb. 

What  to  do.  Make  outline  drawings,  at  least  two  inches  in  diameter,  of  both  gross  and  microscopic 
structure,  labeling  the  bark,  cortex,  mass  of  wood,  woody  bundles,  and  pith. 

In  the  microscopic  sections  compare  the  cell  structure  of  the  woody  bundles. 

CROSS  SECTIONS 


MONOCOTYLEDON 


DICOTYLEDON 


Gross  Structure 


Microscopic  Structure 


[76] 


EXERCISE  71  (Continued) 
LONGITUDINAL  SECTIONS 


MONOCOTYLEDON 


DICOTYLEDON 


Gross  Structure 


Microscopic  Views 


Questions.    1 .  Which  has  more  pith,  a  monocotyledonous  stem  or  a  dicotyledonous  stem  ? 

2.  How  do  the  two  classes  of  plants  differ  as  to  the  character  of  the  wood  ? 

3.  What  is  there  about  the  structure  of  the  dicot  that  suggests  the  possibility  of  longer  life  and 
larger  growth  ? 


[77] 


EXERCISE  72 

Problem.    What  are  the  important  differences  between  monocotyledons  and  dicotyledons  ? 
What  to  use.    Specimens ;  charts  or  results  of  studies  to  furnish  data  for  following  chart. 
What  to  do.    By  means  of  words  or  diagrams  or  both  fill  in  the  following  table,  naming  the  plants 
studied  in  each  case. 


MONOCOTYLEDONS 


DICOTYLEDONS 


External  Structure 


Internal  Structure 


External  Structure 


Internal  Structure 


Cross  Section 


Long  Section 


Cross  Section 


Long  Section 


Shape  and  Veins 


Cross  Section 


Shape  and  Veins 


Cross  Section 


Questions.    1.  How  many  cotyledons  in  the  monocotyledonous  seed?  in  the  dicotyledonous  seed? 

2.  How  do  the  veins  of  the  leaf  run  in  the  monocotyledon  as  compared  with  the  midrib  ?  in  the 
dicotyledon  ? 

3.  What  is  a  polycotyledon  ? 


[78] 


EXERCISE  73 

There  are  ducts,  or  vessels,  through  which  fluids  may  pass  in  the  wood  part  of  a  dicot 
stem  and  in  the  bark  part  of  the  stem.  Some  of  these  ducts  carry  material  up  from  the 
roots  to  the  leaves  ;  others  carry  material  from  the  leaves  to  the  roots.  . 

Problem.    Which  currents  are  carried  by  the  vessels  of  the  bark  ? 

What  to  use.    Two  twigs  of  willow ;  jar  of  water ;  sharp  knife. 

What  to  do.  Cut  off  carefully  a  girdle  of  green  bark  about  an  inch  long,  near  the 
lower  part  of  one  twig ;  place  both  twigs  in  water  for  a  few  weeks  and  observe  from  time 
to  time.  Keep  replacing  evaporated  water,  so  that  the  water  remains  at  a  constant  level. 

Record.  Note  any  changes  that  take  place  in  any  part  of  either  stem,  or  at  the  upper 
or  the  lower  edge  of  the  cut  surface.  From  the  results  observed,  tell  whether  the  bark 
vessels  carry  materials  up  the  stem  or  down. 


i 


Questions.    1.  Explain  reason  for  any  change  noted  in  the  above  experiment. 

2.  Why  does  a  tree  die  when  the  bark  is  girdled  ?    Why  does  it  not  die  immediately  ? 

3.  Why  didn't  the  willow  twig  die  after  girdling  ? 

4.  Is  maple  sirup  obtained  from  the  ascending  sap  or  from  the  descending  sap?    How  can  you  tell? 

5.  Trace  the  upward  and  downward  course  of  sap  in  a  plant 


[79] 


EXERCISE  74 

In  addition  to  the  pressure  resulting  from  the  action  of  osmosis  in  the  root,  and  in  addition  to  the 
apparent  "  pull  "  resulting  from  the  transpiration  of  water  from  the  leaf,  liquids  are  said  to  rise  in  stems 
because  of  the  capillarity  of  the  vessels. 

Problem.  What  is  the  relation  between  the  diameter  of  a  vessel  and  the  height  to 
which  liquids  will  rise  in  it  without  additional  force  being  applied  to  them  ? 

What  to  use.  Glass  tubes  of  various  diameters ;  vessel  containing  water  that  has 
been  colored  with  a  few  drops  of  red  or  blue  ink. 

What  to  do.  Place  the  glass  tubes  vertically  in  the  liquids  ;  note  the  height  to 
which  the  liquid  rises  in  each  tube.  Estimate  the  relative  sizes  of  the  tubes,  in  internal 
diameter. 

Record.  Make  a  diagram  showing  the  approximate  sizes  of  the  tubes  used  and  the  heights  to 
which  the  liquid  rose  in  each.  Tell  what  relation  you  find  between  the  diameter  of  a  vessel  and  the 
extent  to  which  a  fluid  will  be  drawn  up  in  it. 


Questions.    1.  Would  the  vessels,  or  ducts,  of  a  plant  raise  water  as  much  as  glass  tubes,  or  more, 
or  less?  Why? 

2.  For  what  practical  purposes  is  capillary  attraction  used  ? 


[80] 


EXERCISE  75 

I  Problem.    What  is  the  make  up  of  the  human  blood  ? 
What  to  use.    Compound  microscope ;  glass  slide ;  cover  glass ;  gas  or  alcohol  flame ;  sharp  needle ; 
normal  salt  solution  (made  by  dissolving  about  a  teaspoonful  of  common  salt  in  a  pint  of  water).1 

What  to  do.  Press  the  thumb  hard  against  the  joint  of  the  index  finger  until  the  skin  is  tight 
and  red.  With  the  other  hand  pass  the  needle  through  the  flame.  After  waiting  a  moment  for  it  to 
cool,  prick  the  tight  skin  of  the  thumb  with  a  smart  stroke.  Collect  the  drop  of  blood  in  the  middle 
of  the  glass  slide.  Add  a  drop  of  salt  solution.  Cover  with  the  cover  glass.  Examine  under  the 
microscope,  first  with  the  low  power,  then  with  the  high. 

Record.    Make  a  drawing  to  show  all  the  different  structures  you  can  find. 

NOTE.  The  yellowish  disks  are  the  red  corpuscles.  Larger,  irregular  bodies,  not  so  numerous,  are  the  white  corpus- 
cles. The  clear  liquid  in  which  the  corpuscles  float  is  the  plasma.  These  three  are  the  chief  constituents.  There  are  other 
structures  in  the  blood,  but  they  are  harder  to  see. 


Question.    What  element  of  the  blood  is  deficient  in  a  pale  person  who  is  said  to  be  anaemic  ? 


1  It  is  not  necessary  to  prepare  salt  solution  for  your  own  use ;  there  is  probably  some  on  hand  in  the  laboratory. 

[81] 


EXERCISE  76 

Problem.    What  takes  place  when  the  blood  clots  ? 

What  to  use.  Fresh  blood  from  the  butcher  or  the  slaughterhouse,  to  which  a  few  drops  of  for- 
malin have  been  added  as  a  preservative ;  two  glass  beakers  or  battery  jars  with  covers  ;  an  egg-beater 
or  a  bundle  of  thin  twigs ;  water ;  covers  for  jars. 

What  to  do.  Place  equal  quantities  of  blood  in  the  two  vessels.  Set  one  (A)  aside,  covered,  to 
remain  undisturbed.  In  the  other  (B)  beat  up  the  blood  with  the  egg-beater  or  the  twigs.  Draw  out 
what  clings  to  the  beater  after  a  few  minutes.  Cover  and  set  vessel  B  aside  to  remain  undisturbed. 

Wash  the  material  that  clings  to  the  beater  in  fresh  water.  On  the  following  day  examine  the  con- 
tents of  A  and  B. 

Record.  Describe  the  stuff  that  has  been  removed  from  the  blood  by  the  beating.  What  changes 
have  taken  place  in  A  ?  Make  a  diagram  to  show  results.  What  has  happened  in  B  ? 


Questions.    1.  What  is  there  in  A  that  was  not  there  the  day  before? 

2.  Where  did  it  come  from  ? 

3.  Remove  the  clot  from  A  and  wash  in  fresh  water ;  what  change  does  the  washing  bring  about  ? 

4.  What  is  now  absent  from  A  that  was  there  on  the  previous  day  ?    What  has  become  of  it  ? 

NOTE.  The  shiny  stuff  removed  from  the  blood  by  beating  is  fibrin.  This  forms  the  clot.  Plasma  contains  a  substance 
called  fibrinogen  ;  when  this  is  brought  in  contact  with  the  air,  it  becomes  fibrin.  Beating  brings  air  in  contact  with  all  parts 
of  the  plasma  and  removes  the  fibrin  as  fast  as  it  is  formed.  The  clear  fluid  in  the  jar  after  the  clot  is  formed  is  called  serum. 

5.  What  has  become  of  the  corpuscles  in  A  ? 

Blood  =  plasma  +  corpuscles 
Plasma  =  serum  +  fibrinogen 

6.  Why  do  small  cuts  usually  stop  bleeding  in  a  short  while  ?    Why  do  they  sometimes  continue 
to  bleed  for  a  long  while  ? 


[82] 


EXERCISE  77— DEMONSTRATION 

The  blood  carries  not  only  food  and  wastes  but  also  the  gases  involved  in  respiration. 

Problem.    How  do  gases  of  the  air  affect  the  blood? 

What  to  use.    The  blood  from  which  the  fibrin  has  been  removed,1  in  two  beakers ;  oxygen  ;  carbon 

txid  ;  rubber  tube  ;  glass  tube. 
What  to  do.  Connect  the  glass  tube  by  means  of  the  rubber  tube  to  the  tank  or  generator  for  supply 
of  carbon  dioxid.  Pass  a  current  of  the  gas  through  the  blood  (A}  by  placing  the  glass  tube  in  the  blood. 
After  noting  the  action  for  a  few  moments  pass  oxygen  through  the  blood  in  the  second  beaker  (B}. 
After  comparing  effects  reverse  the  procedure ;  that  is,  pass  oxygen  through  A,  and  carbon  dioxid 
through  B. 

Record.  Describe  the  appearance  produced  by  oxygen  and  the  appearance  produced  by  carbon 
dioxid.  Tell  what  happened  to  the  appearance  of  oxygenated  blood  that  was  treated  with  carbon  dioxid 
and  what  happened  when  this  was  again  treated  with  oxygen. 

NOTE.  Blood  contains  an  iron-bearing  protein  in  the  red  corpuscles  called  hemoglobin,  which  has  a  decided  affinity  for 
various  gases  and  forms  with  oxygen  a  chemical  compound  called  oxyhemoglobin.  In  the  presence  of  carbon  dioxid,  hemo- 
globin releases  oxygen  and  takes  up  carbon  dioxid. 


1  Whole  blood  may  be  used  in  which  clotting  has  been  prevented  by  the  addition  of  one  part  sodium  oxalate  solution  (3.8  %) 
to  nine  parts  blood. 

[83] 


EXERCISE  78 


The  blood  is  not  only  constantly  moving  but  also  constantly  changing  its  composition,  for  all  the 
time  materials  are  being  removed  from  it  and  other  materials  are  being  thrown  into  it. 

Problem.  What  are  some  of  the  changes  that  take  place  in  the  blood  at  the  various  points  in  its 
course  ? 

What  to  do.    Gather  all  necessary  information  and  fill  in  the  following  table  : 


SOURCE  OF  THESE 
MATERIALS 

MATERIALS  GIVEN  TO 
THE  BLOOD 

NAME  OF 
ORGAN 

MATERIALS  TAKEN  OUT 
OF  BLOOD 

—  | 

WHAT  BECOMES  OF  THESE 
MATERIALS 

Organs  of  head 

Thyroid 

Lungs 

Muscles  of  arms 

Stomach 

Intestine 

Large  intestine 
when  clogged 

Stiprarenals 

Kidneys 

Liver 

- 

Spleen 

Legs 

[84] 


EXERCISE  79 

The  circulating  fluid,  the  blood,  is  inclosed  in  a  system  of  tubes,  arteries,  veins,  and  capillaries. 
The  motion  of  the  stream  is  caused  by  the  pumping  (muscular  contraction)  of  the  heart  through  which 
the  stream  passes.  The  action  of  the  heart  is  influenced  by  the  chemical  condition  of  the  blood,  and 
this  in  turn  is  influenced  by  our  breathing  and  by  the  work  of  the  body. 

Problem.    How  does  moderate  exercise  influence  the  rate  of  the  heart's  beat  ? 

»What  to  use.    Chart  for  keeping  record  of  class. 
What  to  do.    As  the  teacher  keeps  time  for  one  minute,  count  the  number  of  heart  beats  (pulse) 
during  the  interval.1    After  brisk  two-minute  drill  or  setting-up  exercise,  count  the  pulse  as  before  for 
one  minute. 

Record  your  own  pulse  :     Before  exercise After  exercise  

Record.  In  the  table  below  enter  the  number  of  students  whose  pulse  was  below  75  per  minute 
before  exercising,  the  number  whose  pulse  was  between  76  and  80  inclusive,  and  so  on.  Then  record 
in  the  same  way  the  pulse  rates  after  exercising.2 


PULSE  RATE 

75  OR  UNDER 

76  TO  80 

81  TO  85 

86  TO  90 

91  TO  95 

%TO  100 

101  OR  OVER 

Before  exercising 

After  exercising 

Questions.    1.  What  is  the  lowest  pulse  rate  of  the  class  before  exercising?  after  exercising? 

2.  What  is  the  highest  pulse  rate  before  exercising  ?  after  exercising  ? 

3.  What  is  the  average  pulse  rate  for  the  class  before  exercising  ?  after  exercising  ? 

4.  What  chemical  changes  are  brought  about  in  the  blood  by  exercising  ? 

5.  What  besides  exercise  can  make  your  pulse  become  faster  or  slower  ? 

6.  What  changes  do  these  things  cause  in  the  chemical  condition  of  the  blood  ? 

7.  What  is  the  advantage  or  disadvantage  of  a  changing  pulse  rate  during  exercise  ? 


1  You  can  easily  find  your  pulse  by  pressing  your  finger  directly  in  front  of  your  ear. 

[85] 


2  See  note  in  Exercise  67. 


EXERCISE  80 

Protoplasm  in  plant  and  animal  cells  is  constantly  producing  substances  that  are  of  no  further  use 
to  it,  or  separating  useless  substances  out  of  the  material  received.  Some  of  these  are  passed  out  of  the 
cells  and  out  of  the  organism  ;  others  are  passed  out  of  the  cells  but  gathered  up  in  parts  of  the  organism 
where  they  cannot  injure  the  living  parts. 

Problem.    What  is  the  character  of  some  of  these  waste  substances  ? 

What  to  use.  Petals  of  pansy ;  stem  of  horsetail,  or  scouring  rush  (Equisetuni) ;  Indian  turnip 
(Ariscemc?) ;  microscope  ;  slides  ;  cover  glasses. 

What  to  do.  Mount  piece  of  pansy  petal,  of  scouring  rush,  and  of  Indian  turnip  on  slides  anc 
examine  with  the  microscope.  Note  colored  fluids  and  colored  particles  in  the  pansy ;  crystals  of  silica 
in  the  horsetail ;  crystals  of  lime  oxalate  in  the  Indian  turnip.  Place  a  tiny  bit  of  the  Indian  turnip  or 
the  tip  of  your  tongue  and  note  sensation. 

Record.    Make  clear  diagrams  showing  each  kind  of  body  found  in  your  study  ;  label  structure  shown 

NOTE.  The  peculiar  taste  of  the  Indian  turnip  is  due  to  the  action  of  the  fine  crystals  shown  in  some  of  the  cells 
these  crystals  are  called  raphides  (three  syllables). 


Questions.    1.  What  substances  are  formed  in  living  cells  that  are  not  injurious  to  protoplasm? 

2.  Name  some  substances  that  are  stored  up  in  cells  and  are  of  use  to  the  organism. 

3.  How  can  you  tell  whether  a  given  substance  produced  in  a  cell  is  a  waste  product? 

4.  What  substances  produced  by  protoplasm  are  not  solids  ? 


[86] 


EXERCISE  81 

In  the  simplest  plants  and  animals  the  cell  surface  is  at  the  same  time 
the  absorbing  area  and  the  excreting  area.     In  higher  organisms  many 
of  the  special  surfaces  are  both  absorbing  and  excreting  surfaces  —  for' 
example,  the  lining  of  lungs,  the  leaves  of  plants. 

Problem.  Is  the  root  of  a  plant  an  excreting  organ  as  well  as  an 
absorbing  organ  ? 

What  to  use.  Young  seedlings  of  bean  or  corn  ;  two  bottles  of  water ; 
phenolphthalein  solution. 

What  to  do.  In  one  bottle  place  a  small  quantity  of  phenolphthalein 
that  is  colorless  ;  in  the  other,  enough  alkaline  (red)  phenolphthalein  to 
make  the  water  barely  pink.  In  each  bottle  insert  the  roots  of  a  live 
seedling.  Note  changes  from  time  to  time. 

Record.  Tell  whether  the  roots  give  off  any  substance,  and,  if  so, 
whether  it  is  acid  or  alkaline. 


Questions.  1.  Aside  from  getting  rid  of  waste  matter,  what  use  might  a  secretion  of  substances 
by  the  root  be  to  the  plant  ? 

2.  Compare  the  output  from  your  lungs  with  the  output,  if  any,  of  the  roots,  using  experimental 
methods. 


[87] 


EXERCISE  82 

Problem.    What  is  the  structure  of  an  animal  kidney,  and  what  work  does  it  do  ? 

What  to  use.    A  beef  or  sheep  kidney. 

What  to  do.  Draw  the  outside  view  of  the  kidney  about  three  inches  long.  Cut  through  the  kidney 
lengthwise  and  make  a  second  drawing ;  label  the  arteries  leading  blood  to  the  kidney,  and  veins 
leading  blood  from  the  kidney.  In  section,  note  the  funnel-shaped  cavity  in  which  the  fluid  is  gathered 
by  the  gland  action  of  the  kidney.  Note  the  tube  which  leads  the  waste  to  the  bladder  —  the  ureter. 
Study  a  microscopic  section  or  chart  of  one  of  the  tubules  found  in  the  kidney  —  a  glomerulus  —  and 
draw  below. 


Questions.    1.  In  what  way  is  the  action  of  the  kidney  like  that  of  a  gland  —  for  example,  the  liver? 

2.  In  what  way  is  the  action  of  the  kidney  different  from  that  of  a  gland  ? 

3.  What  are  the  physiological  differences  between  the  wastes  removed  from  the  body  by  the  kidneys 
and  those  removed  by  the  large  intestines  ? 


[88] 


EXERCISE  83 

>   Problem.    What  is  the  structure  of  the  skin  ? 
What  to  use.    A  good  microscopic  section  or  a  chart  or  a  model. 

What  to  do.    Study  the  section  of  the  skin  and  note  a  hair  follicle,  oil  glands,  a  sweat  gland,  nerves 
nd  nerve  endings,  and  the  different  layers  of  skin. 

Record.    Make  a  carefully  labeled  drawing  showing  all  the  structures  mentioned. 


Questions.    1.  Is  the  excretion  of  the  skin  acid  or  alkaline  ?    How  do  you  know  ? 

2.  What  is  the  effect  of  too  frequent  washings  with  soap  ?    Why  not  use  laundry  soap  on  the  skin  ? 

3.  What  is  the  effect  of  too  infrequent  washings  ? 

4.  What  is  a  corn  ?  Why  does  it  hurt  ?  Why  can  we  cut  the  surface  without  causing  pain  ? 

5.  What  animal  coverings  correspond  in  type  to  our  skin  ?    What  animal   coverings  are  of  a 
different  type  ? 


[89] 


EXERCISE  84 


Gather  material  for  completing  the  table  below  with  suitable  sketches  or  statements  of  fact ;  select 
four  types  of  animals  besides  those  named. 

SIX  TYPES  OF  EXCRETORY  ORGANS 


LOCATION  IN  BODY 


NAME  OF  ORGAN 


STRUCTURE  OF  ORGAN 


How  THE  ORGAN  WORKS 


1.  Paramecium 


Contractile  vacuole 


2. 


5. 


6.  Mammal  (man) 


Kidney  with  glomerules 


[90] 


EXERCISE  85 

Plan  an  experiment  or  a  study  to  show  the  effects  of  fatigue  in  some  kind  of  work  or  play. 

Bring  plan  to  class  for  comparison  with  those  of  other  students  and  for  criticism  before  carrying  it  out. 

Make  a  complete  report  on  the  method,  results,  and  conclusions. 


[91] 


EXERCISE  86 

Some  of  the  movements  performed  by  human  beings  and  other  animals  result  from  the  contraction 
of  muscles  over  which  there  is  no  direct  control  (for  example,  heart  movements,  stomach  movements). 
Other  movements  result  from  the  contraction  of  muscles  which  we  can  sometimes  control,  but  which 
ordinarily  act  without  any  attention  from  us  (for  example,  the  eyelid  movements,  diaphragm  move- 
ments). In  still  other  cases  voluntary,  or  striped,  muscles  contract  as  a  result  of  some  stimulation,  without 
our  being  able  to  control  them  at  all.  Such  forced  movements  are  called  reflexes. 

Problem.    Can  we  control  any  of  our  reflexes  ? 

What  to  use.    Live  human  beings  with  definite  reflexes.    (Students  work  in  pairs.) 

What  to  do.  1.  The  knee-jerk  reflex.  Sit  comfortably  on  a  chair,  in  relaxed  position,  with  one  knet 
crossed  over  the  other.  Strike  the  tips  of  the  fingers  just  below  the  kneecap  of  the  upper  knee  and 
note  movement  of  foot  resulting. 

(It  may  require  several  trials  to  locate  the  exact  spot  and  to  learn  the  best  way  of  striking.  A  good 
way  to  proceed  is  to  hold  a  ruler  firmly  with  the  edge  right  under  the  kneecap,  and  then  to  tap  the 
opposite  edge.) 

When  you  have  made  sure  that  you  can  produce  the  knee  jerk,  repeat  several  times,  the  subject 
trying  to  prevent  the  jerk  while  the  operator  produces  the  stimulation. 

2.  The  winking  reflex.    Bring  finger  quickly  in  front  of  subject's  eye,  without  touching  it  or  the 
eyelashes.    Note  movements  of  the  eyelids.    Touch  eyelashes  gently  from  the  side  or  from  above  with 
a  feather  or  light  straw  so  that  the  subject  cannot  see  the  object  approaching.    Repeat,  with  the  subject 
trying  to  prevent  the  wink. 

3.  Grasping  reflex.  If  it  is  possible  to  have  access  to  a  very  young  infant,  note  the  baby's  reaction  to 
a  solid  object  (stick,  finger)  placed  across  the  palm  of  the  hand.    Find  out  whether  the  reaction  is  uniform  ; 
whether  it  depends  upon  the  character  of  the  stimulating  object  —  hard  or  soft,  large  or  small,  rough  or 
smooth,  etc.    With  a  spring  scale  fastened  to  the  object  that  the  baby  clasps,  measure  the  force  of 
the  grip ;  that  is,  find  out  how  hard  one  must  pull  to  force  the  object  out  of  the  baby's  hand, 

Record.  Describe  the  results  of  the  stimulation  in  each  case  and  of  the  attempt  to  prevent  the 
reactions  from  taking  place.  What  is  the  answer  to  the  Problem  ? 

NOTE.  A  reflex  is  a  form  of  movement  that  depends  upon  certain  nerve  connections  which  are  inborn  with  other 
structural  characters  of  the  organism.  The  reflex  system  consists  of  a  receptor  (that  is,  a  receiving  element),  an  effector 
(that  is,  an  effect-producing  element),  and  a  connecting  element.  In  each  of  the  three  elements  there  is  always  a  nerve  part; 
in  the  receptor  there  is  also  a  special  sensitive  portion ;  and  in  the  effector  there  is  a  muscular  (moving)  portion  or  a 
glandular  portion. 


[92] 


EXERCISE  86  (Continued) 


Questions.    1.  Can  you  control  the  tingling  produced  when  the  funny  bone  is  struck  ? 

2.  What  can  you  do  to  prevent  shivering  when  chilled  ? 

3.  Make  a  list  of  all  the  reflexes  you  can  observe  in  various  animals,  and  add  to  it  from  time  to  time. 


[93] 


EXERCISE  87 

In  animals  with  a  brain  there  is  neither  consciousness  of  any  sensation  or  pain,  nor  control  of 
movements,  except  through  the  action  of  brain  cells.  Nevertheless,  many  stimuli  produce  responses,  and 
many  connected  movements  can  be  performed,  after  the  brain  is  removed  or  after  its  connection  with 
the  other  organs  has  been  broken.  This  is  illustrated  by  the  chicken  that  runs  around  after  the  head  is 
cut  off,  or  by  the  snake  that  moves  about  and  withdraws  from  disturbing  contacts  after  the  head  is  removed. 

Problem.    Can  an  animal  make  useful  movements  without  the  action  of  its  brain  ? 

What  to  use.  A  frog  from  which  the  brain  has  been  cut  away  while  under  the  influence  of  chloro- 
form. Some  dilute  hydrochloric  acid. 

What  to  do.  Suspend  the  frog  by  the  lower  jaw  from  a  suitable  support.  Touch  the  side  of  the 
body  lightly  with  a  straw  and  note  any  reactions.  Place  a  small  piece  of  filter  paper  moistened  with  very 
dilute  acid  on  the  side  of  the  body,  and  note  reactions.  Place  the  frog  on  a  table  in  a  sitting  posture  and 
tickle  the  sole  of  the  foot ;  note  response. 

Record.  Describe  the  reaction  of  the  frog  to  the  various  stimuli  applied,  and  show  how  any  of  them 
might  be  considered  of  value  to  a  frog  under  natural  conditions. 


Questions.    1.  Recall  two  changes  in  your  own  behavior  which  may  be  of  use,  but  over  which  you 
have  no  control. 

2.  What  reactions  to  stimuli  do  you  know  in  your  own  body  that  are  of  no  use  to  you  ? 


[94] 


EXERCISE  88 

The  sensitiveness  of  living  things  depends  upon  the  irritability  of  protoplasm ;  but  the  sensitive- 
ness of  a  particular  organ  or  area  of  a  many-celled  animal  depends  upon  the  distribution  of  special 
nerve-endings  in  that  part. 

Problem.    Are  some  parts  of  the  body  surface  more  sensitive  to  touch  than  other  parts  ? 

What  to  use.    Two  students  working  together ;  a  pair  of  dividers  ;  a  ruler. 

What  to  do.  Open  dividers  about  an  inch.  With  the  subject  blindfolded,  apply  the  two  points  at 
the  same  time  on  some  part  of  the  skin  surface,  and  again  but  one  point.  The  subject  is  to  tell  whether 
one  or  two  points  have  been  touched.  Proceed  in  this  way,  opening  or  closing  the  dividers  as  needed, 
until  you  know  the  shortest  distance  that  can  be  distinguished  as  two  separate  points.  Repeat  oil 
different  parts  of  the  body. 

Record.  Tell  the  smallest  separation  between  two  points  that  you  and  your  partner  can  distinguish 
by  touch  in  the  various  regions,  using  millimeter  or  sixteenth  of  an  inch  as  unit. 


WRITER 

FELLOW  WORKER 

Back  of  hand 

.  V..j 

Palm  of  hand 

Tip  of  index  finger 

Back  of  neck 

Face 

Tip  of  tongue 

Questions.    1.  Of  what  practical  significance  are  the  differences  among  the  various  regions? 

2.  Of  what  practical  significance  are  the  differences  among  various  people  ? 

3.  What  other  differences  may  there  be  between  people  as  to  the  sense  of  touch  ? 


[95] 


EXERCISE  89 

Sensitiveness  to  heat  or  cold,  on  the  surface  of  the  body,  depends  upon  the  presence  of  specific 
nerve  endings,  which  are  distributed  rather  unevenly  in  the  skin. 

Problem,    (i)  What  is  the  distribution  of  the  hot  points  and  of  the  cold  points  in  different  parts  o 
the  skin  ?    (2)   Is  there  any  relation  between  the  positions  of  hot  points  and  cold  points  ? 

What  to  use.    Some  pieces  of  wire  or  wire  nails,  about  two  inches  long ;  some  hot  water  (abou 
80°  C.) ;  some  cold  water  (from  5°  to  10°  C.) ;  two  students  working  together. 

What  to  do.  Keep  the  nails  in  the  water,  some  hot  and  some  cold,  except  while  in  actual  use 
Touch  the  tip  of  a  hot  nail  lightly  to  the  skin  of  the  palm  of  the  hand  (using  the  lines  on  the  skin  as 
a  guide),  then  about  one  eighth  of  an  inch  farther,  and  so  on,  noting  at  each  contact  whether  there  is 
a  distinct  sensation  of  heat.  Locate  in  this  way,  on  the  palm  of  the  hand,  from  twenty  to  thirty  ho 
points.  Do  the  same  on  the  cheek  or  on  one  of  the  fingers.  Repeat  with  the  cold  nails.  Change  to 
a  fresh  nail  as  soon  as  the  temperature  of  the  one  in  use  becomes  too  much  like  that  of  the  sur 
rounding  air. 

Record.  Make  a  diagram  of  the  areas  studied.  Locate  the  distribution  of  the  hot  points  by  means 
of  red-ink  dots,  and  that  of  cold  points  by  means  of  black  dots.  Describe  the  results  and  answer  the 
two  questions  in  the  Problem. 


Questions.    1.  About  how  close  together  are  the  hot  points  on  the  skin  ? 

2.  Which  kind  of  nerve  ending  is  more  frequent,  the  cold-perceiving  or  the  hot-perceiving  ?  Would 
this  be  true  in  all  parts  of  the  body  ? 


[96] 


EXERCISE  90 

The  skin,  including  the  mucous  lining  of  the  mouth  and  nose,  can  perceive  several  kinds  of  sensa- 
tions besides  that  of  touch.  Just  as  some  parts  of  the  skin  are  sensitive  to  heat  and  others  to  touch, 
so  different  parts  of  the  tongue  are  sensitive  to  the  different  kinds  of  taste,  of  which  four  are  com- 
monly distinguished  —  sour,  sweet,  salt,  and  bitter.  The  sensitive  elevations  on  the  tongue  are  called 
papillae. 

Problem.    What  is  the  location  of  the  papillae  which  are  sensitive  to  the  different  tastes  ? 

What  to  use.  Four  very  dilute  solutions  :  salt,  sugar,  vinegar  or  citric  acid,  and  quinine  or  aloes ; 
glass  tubes  drawn  to  a  fine  point,  rounded  off ;  water ;  two  students  working  together. 

What  to  do.  With  the  subject  blindfolded,  place  tiny  drops  of  the  different  solutions  on  various 
parts  of  the  tongue,  following  a  systematic  plan,  and  have  the  subject  tell  what  sensation  is  produced 
by  each  drop.  Occasionally  introduce  plain  water.  After  the  drop,  have  subject  rinse  mouth  with 
water ;  rinse  tip  of  tube  if  it  comes  in  touch  with  the  tongue. 

Record.  Make  a  diagram  of  the  tongue  and  locate  the  distribution  of  the  different  kinds  of  papillae, 
using  colored  ink  or  crayon,  or  different  symbols  or  letters,  to  distinguish  the  four  kinds. 


Questions.    1.  Is  it  possible  to  distinguish  two  or  more  tastes  at  the  same  time? 

2.  Do  substances  of  different  taste  ever  interfere  with  our  recognizing  tastes  ? 

3.  How  does    the  order  in  which   different   substances  are   placed   in    the   mouth   influence   our 
perception  ? 

4.  Under  what  conditions  would  it  be  possible  to  put  a  bit  of  salt  or  sugar  in  the  mouth  without 
tasting  it  ? 


[97] 


EXERCISE  91 

With  only  four  kinds  of  taste  sensations  in  the  mouth,  how  is  it  possible  for  us  to  distinguish  such 
a  great  variety  of  food  substances  ?  The  fact  is  that  most  of  the  things  we  relish  or  dislike  affect  us 
through  the  nerve  endings  in  the  nose,  not  through  those  in  the  mouth.  We  discover  flavors  through 
odor  rather  than  through  taste. 

Problem.    Is  it  possible  to  distinguish  flavors  with  the  nose  passages  closed  ? 

What  to  use.  Various  spices,  condiments,  ground  cereals,  fruit  juices,  flavoring  extracts,  beef  juice, 
etc. ;  water ;  two  students  working  together. 

What  to  do.  With  the  subject  blindfolded  and  holding  the  nose  firmly  with  the  fingers,  place  suc- 
cessive drops  or  fragments  of  the  various  materials  to  be  tried  on  the  tongue,  and  have  the  subject 
identify  them  if  possible.  Rinse  the  mouth  after  each  trial,  before  opening  the  nose.  In  case  of 
inability  to  identify,  open  the  nose  before  removing  substance.  Have  both  students  take  turns  as  subject. 

Record.  Keep  a  close  record  of  the  materials  tried  and  the  results  of  each  trial,  whether  a  success- 
ful identification,  a  failure,  or  a  partial  success. 

NOTE.  The  nasal  passages  connect  with  the  pharynx,  the  cavity  back  of  the  mouth ;  but  with  the  nostrils  closed  it  is 
impossible  for  a  current  of  air  to  carry  materials  from  the  mouth  to  the  sensitive  odor  area. 


Questions.    1.  How  is  it  possible  to  be  sensitive  to  flavors  but  not  keen  as  to  tastes? 

2.  What  effect  has  a  cold  in  the  nose  upon  our  appreciation  of  food  ? 

3.  Which  class  of  sensations  more  easily  affects  our  feelings  of  pleasure  or  disgust  —  taste  or  odor  ? 


[98] 


EXERCISE  92 

The  eye  in  backboned  animals  and  in  certain  mollusks  (the  octopus,  for  example)  consists  of  a  lens 
that  projects  an  image  upon  a  sensitive  surface,  the  retina.  The  focusing,  instead  of  being  brought 
about,  as  in  a  camera,  by  changing  the  distance  between  the  lens  and  the  retina,  is  brought  about  by 
changing  the  convexity,  or  bulge,  of  the  lens.  Very  few  human  eyes  are  perfect,  although  most  of 
them  are  quite  usable  for  all  ordinary  purposes.  The  most  frequent  defects  are  nearsightedness 
and  farsightedness,  and  an  unevenness  of  the  curvature  called  astigmatism. 

Problem.    What  condition  of  the  eye  brings  about  farsightedness  or  nearsightedness  ? 

What  to  use.    A  convex  lens  ;  a  vertical  screen  or  sheet  of  paper  held  in  a  vertical  position  ;  a  ruler. 

What  to  do.  Support  the  lens  in  a  vertical  position  a  measured  distance  from  the  window — say 
100  or  1 20  inches.  Place  the  screen  back  of  the  lens  and  move  it  backward  and  forward  until  you 
have  a  clear  image  of  the  window.  Measure  the  distance  between  the  lens  and  the  screen ;  this  is  the 
focal  distance.  Now  bring  the  lens  five  or  six  inches  nearer  the  window,  focus  again,  and  measure 
the  focal  distance.  Move  the  lens  five  or  six  inches  farther  from  the  window  and  find  the  third 
focal  distance. 

Record. 


DISTANCE  OF  OBJECT  FROM  LENS 

FOCAL  DISTANCE 

in. 

in. 

—  c  ///..  = 

in. 

-f-  c  in.  = 

in. 

From  the  measurements  made,  can  you  tell  what  condition  of  the  eyeball  brings  about  farsightedness 
and  what  condition  brings  about  nearsightedness  ? 


Questions.    1.  If  the  eyeball  is  too  short,  what  can  be  done  to  save  eyestrain  ? 

2.  If  the  eyeball  is  too  long,  what  can  be  done  to  save  eyestrain  ? 

3.  Why  is  a  person  more  likely  to  need  spectacles  at  an  advanced  age  than  at  an  early  age  ? 


[99] 


EXERCISE  93 

There  are  many  organisms  that  respond  to  light  without  being  able  to  see  things  as  we  see  them, 
and  some  of  them  do  not  even  have  eyes. 

Problem.    How  does  an  organism  without  eyes  respond  to  light  ? 

What  to  use.    Live  earthworms  ;  glass  or  enamel-ware  dish  ;  some  earth. 

What  to  do.  Place  earthworm  in  empty  dish  which  has  been  moistened.  Hold  it  so  that  the  light 
strikes  it,  and  note  the  character  and  direction  of  its  movements.  Change  position  of  dish  to  get  illumi- 
nation from  different  directions.  Place  earth  in  the  dish  and  the  worm  on  top  of  the  earth  ;  note 
whether  the  movements  with  relation  to  light  are  different  on  the  earth.  After  the  animal  has  started 
to  burrow,  note  the  effect  of  stronger  or  weaker  illumination  on  the  exposed  parts. 

Record.    Describe  the  movements  of  the  animals  under  different  conditions  and  degrees  of  illumination. 


Questions.    1.  What  other  organisms  without  eyes  do  you  know  to  be  sensitive  to  light  ? 

2.  Can  you  tell  whether  the  front  end  or  the  rear  end  of  the  earthworm  is  more  sensitive  ? 

3.  How  can  you  tell  that  the  movements  observed  were  not  responses  to  odor  ? 

4.  What  other  forces  appear  to  influence  the  movements  of  the  earthworm  besides  light  ? 


[100] 


EXERCISE  94  \  t  .-/,  \ 

Vibrations  of  certain  kinds  are  received  through  the  ear  and  interpreted  as  sound.  In  different 
kinds  of  animals  these  vibrations  are  perceived  through  other  kinds  of  organs,  as  by  hairs  on  the 
antennae  of  mosquitoes  and  the  "drums"  on  the  front  legs  of  crickets. 

Problem.    What  kinds  of  ears  have  animals  other  than  mammals  ? 

What  to  use.    Living  or  preserved  frog  and  grasshopper  ;  magnifier. 

What  to  do.  Study  the  external  eardrum  of  the  frog  and  the  tympanum  of  the  grasshopper  on  its 
first  abdominal  segment,  for  size,  shape,  and  rigidity  or  flexibility.  If  you  have  live  specimens,  determine 
whether  they  are  sensitive  to  sounds  that  are  different  in  pitch,  loudness,  or  other  quality. 

Record.    Describe  results  of  your  observations.    Make  diagrams  showing  structures. 


Questions.    1.  What  organisms  do  you  know  that  are  not  affected  by  sounds  ? 

2.  How  do  you  know  they  are  not  affected  ? 

3.  Under  what  living  conditions  would  perception  of  sounds  be  of  no  use  to  an  organism  ? 

4.  What  practical  applications  are  made  of  the  principle  of  vibration  illustrated  by  the  action  of  an 

eardrum  ? 


[101] 


:- 1  I';  t  :  "  \  t         :  -.  ^    :  EXERCISE  95 

Problem.  Do  the  two  ears  of  a  person  differ  from  each  other  in  acuteness  of  hearing  in  the  same 
way  as  the  ears  of  different  people  do  ? 

What  to  use.    A  class  of  students  ;  a  watch  with  a  reasonably  loud  tick ;  a  tape  measure. 

What  to  do.  Blindfold  each  person  in  turn.  Bring  watch  slowly  toward  the  right  ear  until  the 
subject  can  just  begin  to  hear  it ;  measure  the  distance.  Repeat  for  the  left  side. 

Record.    Distance  in  inches  at  which  right  ear  detected  tick ;  left  ear 

Make  a  table  showing,  by  the  distance  in  inches  at  which  the  tick  was  heard,  the  relative  acuteness 
of  hearing  of  each  subject  for  the  right  ear  and  for  the  left  ear,  and  the  difference  between  the  two. 


RIGHT  EAR 

LEFT  EAR 

DIFFERENCE 

RIGHT  EAR 

LEFT  EAR 

DIFFERENCE 

RIGHT  EAR 

LEFT  EAR 

DIFFERENCE 

•: 

1 .  What  is  the  average  difference  between  the  two  ears  ? 

2.  What  is  the  range  of  variation  between  the  best  and  the  poorest  right  ear  ? 

3.  What  is  the  range  of  variation  between  the  best  and  the  poorest  left  ear  ? 

4.  What  is  the  average  distance  for  the  right  ear  ? 

5 .  What  is  the  average  distance  for  the  left  ear  ? 

6.  Why  is  the  difference  between  the  averages  less  than  the  average  difference  ? 

Questions.    1.  In  what  other  respects  besides  acuteness  do  people's  hearing  sensations  differ? 

2.  What  practical  use  can  be  made  in  school  of  the  fact  that  some  hear  so  much  more  easily 
than  others  ? 

3.  What  practical  use  can  be  made  of  this  fact  outside  of  school  ? 

4.  What  is  meant  by  the  statement  "  If  there  were  no  ears,  there  would  be  no  sound  "  ? 


[102] 


EXERCISE  96 

The  semicircular  canals  are  our  balancing  organs,  as  changes  in  their  positions  result  in 
a  stimulation  of  nerve  endings  in  their  lining. 

Problem.    How  sensitive  is  an  animal  to  changes  in  its  position  ? 

What  to  use.    A  live  frog  in  a  battery  jar ;  lampblack  ;  absorbent  cotton  ;  vaseline. 

What  to  do.  1.  When  the  frog  is  at  rest,  slowly  rotate  the  jar  to  right  or  left  (3O°-45°)  without 
shaking  it ;  reverse  the  movement.  Note  reactions  of  frog.  Hold  the  jar  up  so  that  you  can  see  the  side 
of  the  animal,  and  tilt  the  jar  forward  and  backward,  noting  reaction.  Hold  the  jar  up  so  that  you  face 
the  frog,  and  tilt  it  to  the  right  and  to  the  left,  noting  reactions. 

2.  To  see  whether  any  of  these  responses  are  influenced  by  sight,  mix  a  little  vaseline  and  lamp- 
black, and  rub  the  mixture  into  a  piece  of  moist  absorbent  cotton.  With  this  pad  you  can  blindfold  the 
frog  without  hurting  or  irritating  it.  (Repeat  the  displacements  as  in  i .) 

Record.  Describe  the  responses  of  the  frog  to  changes  in  bodily  position,  and  try  to  answer  the 
question  in  the  Problem. 


Questions.    1.  What  evidence  did  you  discover  that  the  frog  is  influenced  by  the  direction  from 
riiich  the  light  strikes  it  ? 

2.  How  would  you  find  out  whether  the  frog  would  behave  in  the  same  way  if  it  ttsed  its  eyes  only  ? 

3.  What  practical  use  can  be  made  of  the  fact  that  some  people  are  more  sensitive  to  changes  in 
position  than  others  ? 

4.  What  evidence  is  there  that,  besides  the  semicircular  canals,  other  organs  and  sensations  help 
us  to  keep  erect  and  walk  straight  ? 


[103] 


EXERCISE  97 

We  saw  (Exercise  86)  that  some  of  our  reflex,  or  instinctive,  movements  result  from  the  contractions 
of  muscles  which  we  can  control.  We  can  produce  some  of  these  movements  at  will,  and  we  can  also 
inhibit,  or  prevent,  some  of  the  movements. 

Problem.    How  many  trials  does  it  take  to  overcome  the  winking  reflex  ? 

What  to  use.    A  sheet  of  glass ;  a  rubber-tipped  pencil  or  stick ;  two  students  working  together. 

What  to  do.  Have  subject  hold  pane  of  glass  in  front  of  face  while  operator  from  time  to  time 
strikes  opposite  side  of  glass  before  one  or  the  other  eye.  Subject  tries  to  keep  from  winking,  confi- 
dent that  pencil  cannot  reach  him.  Note  number  of  strokes  before  there  is  complete  control.  Change  off. 

Record.    Describe  observations  and  results. 

How  many  attempts  were  necessary  to  secure  complete  inhibition  ? 

How  many  attempts  were  necessary  for  your  fellow  worker  ? 

Tabulate  results  for  the  whole  class  : 


NUMBER  OF 
TRIALS 

NUMBER  OF 
STUDENTS  FOR 
EACH  SCORE 

What  was  the  highest  number  of  trials  ? 
What  was  the  lowest  number  of  trials  ? 
What  was  the  average  number  of  trials  ? 


Questions.    1.  What  is  the  advantage  of  being  able  to  overcome  an  impulse  within  a  short  time  or 
after  a  few  trials  ? 

2.  What  is  the  disadvantage  ? 

3.  Do  boys  or  girls  learn  to  control  their  impulses  more  readily  ?    How  do  you  know  ? 

4.  What  kinds  of  inhibitions  are  established  most  easily  ?    What  kinds  least  easily  ? 

5.  What  evidence  is  there  that  other  animals  can  learn  to  overcome  natural  impulses  ? 


[104] 


EXERCISE  98 

§  Below  are  the  names  of  ten  organisms,  including  four  kinds  of  plants  and  six  kinds  of  animals. 
At  the  top  of  each  blank  column  enter  the  name  of  a  process  or  activity  that  all  ten  living  things 
show  in  common.     In  the  appropriate  spaces  indicate  briefly  the  organs  or  methods  by  which  the 
named  activities  or  processes  are  carried  on. 


ORGANISM 


Ameba 


Yeast 


Starfish 


Fern 


Oyster 


Cabbage 


Bedbug 


Oak  tree 


Crab 


American 
citizen 


Questions.  1.    Which  of  the  processes  or  activities  named  are  essential  to  life  ?    Mark  with  A. 
2.  Which  of  the  organs  mentioned ^re  essential  to  life?    Mark  with  X. 


[105] 


EXERCISE  99 

Nutrition  is  a  process  going  on  in  every  living  cell,  and  many  of  the  activities  of  a  many-celled 
organism  are  related  to  nutrition.  In  the  spaces  of  the  table  tell  briefly  what  organs  and  processes  of  the 
organism  as  a  whole  carry  forward  nutrition,  and  also  what  structures  and  processes  in  the  individual 
cell  mentioned. 

NUTRITION  STRUCTURES  AND  PROCESSES 


The  frog  as  a  whole 


The  potato  plant 


A  cell  in  the  muscle  of  the  frog's  leg 


A  cell  in  the  bark  of  'the potato 's  tuber 


[106] 


EXERCISE  100 

Respiration  is  related  primarily  to  the  release  of  energy  in  protoplasm.  It  is  carried  on  by  every 
living  cell.  In  many-celled  organisms  we  find  a  variety  of  structures  and  processes  related  to  respiration. 
Respiration  involves  an  intake  and  an  output  of  gases.  In  the  spaces  below  tell  briefly  what  structures 
and  processes  are  involved  in  the  respiration  of  the  named  organism  and  in  the  respiration  of  the 
individual  cells  mentioned. 


STRUCTURES  AND  PROCESSES  INVOLVED  IN  RESPIRATION 


INTAKE 


OUTPUT 


Grasshopper 


Cell  in  a  diges- 
tive gland  of 
a  grasshopper 


Willow  tree 


Cambium  cell 
in  the  stem  of 
a  willow 


[107] 


EXERCISE  101 

Many  of  the  substances  resulting  from  the  metabolism  in  a  cell  (the  chemical  changes  going  on  in 
protoplasm)  are  injurious  to  protoplasm  and  must  be  removed  if  the  cell  is  to  continue  living.  In 
many-celled  organisms  various  structures  and  processes  are  related  to  excretion. 

In  the  table  below  enter  in  the  appropriate  spaces  the  names  of  the  materials  thrown  out  and  the 
structures  and  processes  involved  in  excretion. 

EXCRETION  FROM  LIVING  CELLS  AND  FROM  ORGANISMS 


EXCRETED  SUBSTANCES 


EXCRETING  STRUCTURES  AND  PROCESSES 


Human  being 


Cell  of  gray 
matter  in 
spinal  cord 


Apple  tree 


Palisade  cell 
of  leaf 


[108] 


EXERCISE  102 


In  some  ways  the  nutrition  processes  in  all  living  things  are  very  much  alike ;  but  every  class  of 
plants  or  animals,  and  in  many  cases  every  species,  has  its  own  peculiarities.  In  the  following  table 
describe  briefly  the  resemblances  in  the  matter  of  nutrition,  and  also  .the  distinctive  structures  and 
processes,  of  each  organism  named. 


I 


RESEMBLANCES 


DISTINCTIVE  STRUCTURES  AND  PROCESSES 


Paramecium 


Bean  plant 


Clam 


Butterfly  (larva) 


Butterfly  (adult} 


Man 


[109] 


EXERCISE  103 

Inspiration  of  oxygen  and  expiration  of  carbon  dioxid  take  place  in  practically  every  plant  and  every 
animal,  but  every  class  of  organisms  shows  some  distinctive  structures  and  processes  in  relation  to 
breathing. 

In  the  table  below  indicate  briefly  what  the  organisms  named  have  in  common  (with  regard  to 
respiration)  and  in  what  processes  or  structures  their  respiration  differs. 

RESEMBLANCES  AND  DIFFERENCES  AMONG  ORGANISMS  WITH  RESPECT  TO  RESPIRATION 


RESEMBLANCES 


DISTINCTIVE  STRUCTURES  AND  PROCESSES 


Spirogyra 


Potato  beetle 


Perch 


Frog 


Robin 


[110] 


EXERCISE  104 

Every  living  cell  and  every  living  organism  must  get  out  of  its  protoplasm  the  injurious  by-products 
of  metabolism  ;  but  different  organisms  accomplish  this  result  in  different  ways. 

In  the  following  table  indicate  in  what  ways  the  plants  and  animals  named  get  rid  of  their  wastes, 
pointing  out  first  their  resemblances  and  then  their  distinctive  structures  and  activities. 

RESEMBLANCES  AND  DIFFERENCES  OF  VARIOUS  ORGANISMS 
WITH  RESPECT  TO  EXCRETION 


RESEMBLANCES 


DISTINCTIVE  STRUCTURES  AND  PROCESSES 


Diphtheria 
bacillus 


Earthworm 


Frog 


Questions.    1.  In  what  respects  does  excretion  resemble  respiration? 

2.  In  what  respects  do  these  two  processes  differ  ? 

3.  In  what  ways  can  wastes  be  made  harmless  to  the  organism  besides  expelling  them  from  the  system  > 


[111] 


EXERCISE  105 

While  all  protoplasm  can  contract,  not  all  organisms  can  move  about.  Different  types  of  plants 
and  animals  show  distinctive  modes  of  locomotion  and  distinctive  ways  of  moving  in  relation  to  getting 
food  and  in  relation  to  escape  from  enemies.  Organs  that  behave  in  the  same  way  with  relation  to  the 
organism's  living  are  said  to  be  analogous,  even  if  they  are  really  different  kinds  of  organs  —  for  example, 
the  wings  of  insects,  of  birds,  and  of  bats.  Organs  that  have  the  same  kind  of  origin  and  structure  are 
said  to  be  homologous,  even  if  they  are  used  differently  —  for  example,  the  claws  of  a  cat  and  the  toes 
of  an  elephant,  the  balancers  of  a  house  fly  and  the  hind  wings  of  a  moth. 

In  the  table  below  indicate  the  organs  of  locomotion  distinctive  of  each  type  of  organism  mentioned, 
and  tell  in  what  medium  it  works  and  how  it  is  used. 


TYPES  OF  LOCOMOTIVE  ORGANS  AND  ACTIVITIES 


NAME  OF  TYPE 

NAME  OF  ORGANS 

How  USED 

MEDIUM 

Ameba 

-' 

Typhoid  bacillus 

Worm 

(Name) 

Mollusk 

(Name) 

Insect 

(Name) 

Crustacean 

(Name) 

Fish 

(Name) 

Toad  (larva) 

Toad  (adult) 

Alligator 

Ostrich 

" 

Monkey 

[112] 


EXERCISE  105  (Continued) 

Go  over  the  list  of  organs  named  and  place  the  letter  a  after  the  first  one  and  after  all  the  others 
that  are  homologous  with  it ;  then  place  the  letter  b  after  the  first  one  not  yet  marked  and  after  each  one 
that  is  homologous  with  it ;  then  mark  a  third  group  with  the  letter  c  ;  and-  so  on  until  all  are  checked  off. 

Go  over  the  list  again  and  mark  with  a  capital  A  the  first  one  and  all  that  are  analogous  with  it ; 
then  mark  with  a  letter  B  all  that  are  analogous  with  each  other  but  not  with  the  first  group ;  and  so  on. 


Questions.    1.  What  are  the  greatest  differences  that  you  have  observed  between  organs  that  are 
homologous  ? 

2.  What  are  the  most  diverse  organs  that  you  have  observed  as  having  a  similar  function  ? 

3.  What  is  suggested  by  a  study  of  analogies  and  homologies  concerning  the  plasticity  of  protoplasm  ? 


[113] 


EXERCISE  106 

All  protoplasm  is  irritable,  but  not  all  organisms  have  special  sense  organs.  While  the  reactions 
of  organisms  to  stimulation  often  bring  them  into  more  favorable  positions  with  relation  to  the  environ- 
ment, not  every  sensation  or  every  response  is  necessarily  of  benefit  to  the  organism. 

In  the  following  table  indicate  the  responses  of  the  organisms  named  to  the  different  kinds  of 
stimulation,  and  the  value  of  these  responses  to  them. 


STIMULI 

Touch 

Chemical 

Light 

Reaction 

Value  of  Reaction 

Reaction 

Value  of  Reaction 

Reaction 

Value  of  Reaction 

Ameba 

•' 

Crayfish 

• 

Night 
moth 

Man 

Question.    What  are  some  plant  and  animal  reactions  that  are  injurious  to  the  organisms  ? 


[114] 


EXERCISE  107 

While  all  living  things  must  have  the  same  nutrients  (proteins,  fuels,  etc.),  they  do  not  all  get  their 
from  the  same  sources.  And  while  all  organisms  must  take  into  themselves  certain  materials  from 
;ir  environment,  they  do  not  all  seize  and  ingest  their  food  in  the  same  way. 

In  the  following  table  indicate  the  sources,  the  organs,  and  the  modes  of  ingestion  that  are 
iracteristic  of  the  feeding  of  the  organisms  named. 


FOOD-GETTING  AND  FOOD-INGESTION  OF  VARIOUS  TYPES  OF  ORGANISMS 


TYPE  OF  ORGANISM 


NATURE  OF  FOOD 


ORGANS 


PROCESSES 


Ameba 


Maple  tree 


Sponge 


rapeworm 


Ground  beetle 


Mosquito 


Snake 


Barn  swallow 


Cat 


[115] 


EXERCISE  108 

The  exchange  of  material  between  an  organism  and  its  environment,  in  nutrition,  in  respiration,  and 
in  excretion,  takes  place  through  the  general  body  surface  or  through  special  surfaces.  In  many  organisms 
the  total  amount  of  metabolism  therefore  depends  directly  upon  the  total  amount  of  surface  that  can  be 
exposed. 

Problem.    Does  not  the  amount  Of  surface  of  a  body  vary  directly  with  the  size  of  the  body  ? 

What  to  use.    A  number  of  cubical  blocks  of  the  same  size,  wooden  or  clay. 

What  to  do.  Since  the  blocks  are  all  the  same  size,  we  may  count  the  edge  of  a  block  as  the  unit 
of  length  (for  example,  i  inch,  i  centimeter),  one  face  of  a  cube  as  the  unit  of  area  (for  example, 
I  square  inch,  i  square  centimeter),  and  so  on.  Build  up  sets  of  blocks  having  one,  two,  three,  die. 
inches  as  a  base,  with  the  same  width  and  height,  and  note  the  total  amount  of  exposed  surface  each 
such  cubical  pile  has.  The  cubical  measure  may  be  taken  as  proportional  to  the  mass  or  weight  of  the 
body  represented  by  such  a  pile.  Note  the  relation  between  the  surface  of  a  cube  and  its  mass. 

Record.    In  the  table  enter  the  observed  or  calculated  surface  and  the  volume  of  mass  for  a  cube 
of  each  dimension. 


LENGTH  IN 
INCHES 

AREA  IN  SQUARE 
INCHES 

VOLUME  IN  CUBIC 
INCHES 

LENGTH  IN 
INCHES 

AREA  IN  SQUARE 
INCHES 

VOLUME  IN  CUBIC 
INCHES 

1 

6 

2 

7 

3 

8 

4 

9 

5 

10 

Questions.    1.  What  effect  upon  its  volume  has  the  doubling  of  the  dimensions  of  an  object? 

2.  What  effect  upon  its  surface  has  the  doubling  of  the  dimensions  of  an  object  ? 

3.  Does  the  ratio  of  surface  to  volume  remain  constant  ?   Why  ? 

4.  How  would  you  arrange  eight  blocks  to  get  the  largest  amount  of  surface  exposed  ? 

5.  How  would  you  arrange  eight  blocks  to  get  the  smallest  amount  of  surface  exposed  ? 

6.  What  is  the  effect  of  growth  upon  the  relative  amount  of  absorbing  surface  ? 

7.  What  kinds  of  organisms  are  capable  of  indefinite  growth  ? 

8.  What  are  some  of  the  ways  in  which  the  structure  of  an  absorbing  or  discharging  surface  makes 
for  a  large  area  ? 


[116] 


EXERCISE  109  -DEMONSTRATION 

When  part  of  a  plant  or  of  an  animal  is  cut  off,  in  some  cases  the  surface  merely  heals  up,  while 
other  cases  the  whole  of  the  missing  part  is  regrown. 
Problem.    How  much  can  be  regrown  if  half  of  a  worm  is  cut  off  ?  ' 
What  to  use.    A  live  earthworm  or  a  live  Planaria  (flatworm) ;  sharp  knife  or  scissors. 
What  to  do.    Cut  the  animal  into  two  close  to  the  middle,  and  return  to  earth  or  water  for  further 
)servation. 

Record.    Describe  the  response  of  the  animal  to  the  section,  and  the  changes  to  be  noted  from 
ime  to  time  —  say  at  intervals  of  two  days.    Make  drawings  showing  what  happened  to  each  part,  as 
well  as  the  appearance  of  the  worm  before  the  operation. 


Questions.    1.  What  practical  use  can  be  made  of  the  fact  that  organisms  can  regrow  removed  parts? 
2.  What  is  the  difference  between  the  regeneration  of  roots  on  a  slip  or  cutting  and  the  formation 
)f  a  new  plant  from  a  bulb  or  tuber  ? 


[117] 


EXERCISE  110 

Problem.    What  are  the  early  stages  in  the  development  of  a  backboned  animal  from  the  egg  ? 
What  to  use.    Fresh  frog  eggs  or  fish  eggs 1 ;  magnifiers  ;  microscope. 
What  to  do.    Watch  the  eggs,  with  unaided  eye,  with  magnifying  glass,  and  with  microscope,  to 
note  changes  that  take  place  from  time  to  time. 

Record.    Make  drawings  to  show  the  stages  observed. 


Questions.    1.   How  does  the  single  cell  become  a  many-celled  body? 

2.  At  what  point  do  the  cells  appear  to  be  of  two  or  more  different  kinds  ? 


1  If  live  eggs  are  not  available,  make  study  from  models  or  from  charts. 

[118] 


EXERCISE  111 

Problem.    How  do  eggs  of  mosquitoes  change  into  adults  ? 

What  to  use.    Glass  jar  or  tumbler ;  cheesecloth ;  large  magnifying  glass. 

What  to  do.     Get  some  fresh  pond  water ;  have  glass  about  two-thirds  full. 

;ave  water  in  glass  exposed  out  of  doors  overnight ;  in  the  morning  examine 

le  surface  of  the  water  for  mosquito  eggs.    If  any  are  found,  cover  glass  with 

icesecloth.    Then  study  with  magnifying  glass  from  day  to  day  to  note  changes 

lat  take  place. 

Record.  Make  drawings  to  illustrate  the  changes  noted.  Describe  move- 
icnts  of  larvae  etc. 


Questions.    1.  How  many  eggs  were  there?    How  many  hatched  out? 

2.  How  can  you  tell  whether  the  mosquitoes  that  hatch  out  in  the  glass  are  infected  with  malaria 
some  other  disease  parasite  ? 


[119] 


EXERCISE  112 

The  conditions  for  development  and  the  conditions  for  growth  are  usually  but  not  always  the  same 
for  a  given  plant  or  animal.  Part  of  the  life  cycle  may  be  passed  in  the  winter  and  another  part  in 
the  summer,  so  that  the  most  favorable  temperature  may  not  be  the  same  for  growth  as  for  later  changes. 

Problem.  What  is  the  effect  of  high  temperature  on  the  development  of  an  insect  that  normally 
spends  parts  of  its  resting  stage  in  the  cold  ? 

What  to  use.    A  number  of  cocoons  or  pupae  of  some  common  insect,  gathered  in  the  fall. 

What  to  do.  Place  some  of  the  cocoons  in  a  battery  jar  in  the  classroom  ;  leave  others  in  a  jar 
or  box  out  of  doors.  Watch  from  time  to  time  to  anticipate  an  early  emergence  of  the  adult.  Date 
the  insects  as  they  come  out.  When  the  last  of  the  brood  has  emerged,  make  comparisons  as  to  size, 
patterns,  etc. 

Record.    Describe  the  results  and  your  conclusions. 


Questions.    1.  How  can  you  tell  that  the  inside  of  the  cocoons  kept  indoors  was  warmer  than  in 
the  case  of  those  that  remained  out  of  doors  ? 

2.  Is  the  difference  in  temperature  between  the  indoor  pupae  and  the  outdoor  pupae  the  same  as 
the  difference  between  the  classroom  and  the  out  of  doors  ?    How  do  you  know  ? 

3.  What  advantages  or  disadvantages  are  indicated  by  any  differences  in  development  that  you 
discovered  ? 


[120] 


EXERCISE  113 


The  spores  of  various  plants  are  usually  so  small  that  single  ones  cannot  be  seen  without  a  micro- 
scope. They  are  thus  blown  about  in  the  dust. 

Problem.     How  widespread  are  the  spores  of  common  spore-producing  plants  ? 

What  to  use.  Pieces  of  moist  bread  or  diluted  sirups  or  fruit  juices  (a  teaspoonful  to  a  pint  of  water), 
to  catch  the  spores ;  moist  chambers  (consisting  of  a  tumbler  inverted  over  several  thicknesses  of  moist 
filter  paper  or  blotter),  to  hold  the  bread  ;  test  tubes,  closed  with  cotton  plugs,  to  hold  the  sirups. 

What  to  do.  Expose  pieces  of  bread  or  tubes  of  sirup  in  various  situations  overnight ;  cover  and 
leave  in  a  dark  cupboard  or  under  a  box,  at  ordinary  temperature  or  warmer.  Examine  at  intervals 
i  of  twenty-four  hours  and  note  numbers  and  kinds  of  growths. 

Record.  Describe  the  results  from  different  sources  and  make  up  your  mind  where  different  kinds 
of  spores  are  likely  to  be  most  abundant.  If  it  is  possible  to  examine  with  a  microscope,  add  drawings 
to  record. 


Questions.     1.  Do  all  kinds  of  dust  contain  spores? 

2.  What  kinds  of  growth  are  most  likely  to  come  from  the  dust  in  a  closely  populated  neighborhood  ? 

3.  What  kinds  of  spores  are  most  likely  to  be  found  in  the  woods  ? 


[121] 


EXERCISE  114 

Problem.    How  does  conjugation  take  place  in  a  simple  plant  ? 

What  to  use.    Microscope  ;  slides  and  cover  glasses  ;  pond  scum  —  Spirogyra. 

What  to  do.  Mount  Spirogyra  and  examine  with  microscope,  to  learn  the  structure  of  the  cell,  the 
nucleus,  and  the  chlorophyl  band.  Bits  of  Spirogyra  from  the  bottom  of  the  jar,  when  they  begin  to 
change  color,  should  be  examined  for  conjugation  stages ;  these  will  be  recognized  by  the  fact  that  two 
threads  lie  close  together,  with  outgrowths  reaching  across,  forming  a  ladder-shaped  arrangement.  Note 
any  changes  going  on  in  any  part  of  the  cell. 

Record.    With  the  aid  of  diagrams  describe  the  stages  found  and  the  end  result. 


Questions.    1.  Are  all  the  empty  cells  in  one  thread,  or  are  there  some  empty  cells  in  each  thread  ? 

2.  Are  the  cells  of  one  thread  (before  conjugation)  distinguishable  from  those  of  the  other  thread  - 
in  size,  in  structure,  in  color,  or  in  any  other  way  ? 

3.  How  does  the  zygote  resulting  from  conjugation  differ  from  a  spore  ? 


[122] 


EXERCISE  115 

Problem.    How  do  spores  look,  and  how  do  they  start  new  plants  ? 

What  to  use.  Microscope  ;  slides  ;  cover  glasses  ;  dissecting  needle  ;  water  ;  sugar  ;  spores  of  vari- 
ous kinds,  including  pollen  grains  from  flowers. 

What  to  do.  Place  a  few  spores  in  a  drop  of  very  dilute  sirup  on  a  glass  slide  by  touching 
needle  to  an  anther  and  then  touching  it  to  the  drop  of  sirup.  Do  the  same  with  spore  masses  of 
mold  growing  on  bread,  fruit  rinds,  or  cheese.  Leave  in  moist  chamber  overnight.  Cover,  and  examine 
with  microscope. 

Record*  By  means  of  drawings  and  words  show  the  appearance  of  spores  used  and  of  the  begin- 
ning of  new  plants. 


Questions.    1.  In  what  ways  do  growths  from  pollen  grains  resemble  growths  from  other  spores? 
2.   How  do  growths  from  pollen  grains  differ  from  other  spore  products  ? 


[123] 


EXERCISE  116 

The  flower  is  the  seed-producing  part  of  a  plant,  although  the  part  that  we  usually  notice  is  not  the 
one  that  makes  seeds. 

Problem.    What  are  the  organs  of  a  flower,  and  how  do  they  make  seeds  ? 

What  to  use.  A  complete,1  regular,2  and  perfect3  flower,  such  as  the  tulip  or  wild  rose;  a 
magnifying  glass. 

What  to  do.    Examine  the  parts  of  the  flower  and  their  arrangement. 

NOTE  I .  The  parts  of  the  flower  are  arranged  in  circles,  or  rings,  and  are  all  attached  to  an  enlargement  of  the  end  of 
the  stalk,  called  the  receptacle. 

NOTE  2.  The  outer  circle  is  called  the  calyx;  and  its  parts,  which  may  be  quite  distinct  or  more  or  less  fused 
together,  are  called  sepals. 

NOTE  3.  The  second  circle  (from  the  outside)  is  called  the  corolla ;  and  its  parts,  which  may  be  distinct  or  united, 
are  petals. 

NOTE  4.  The  calyx  and  corolla  together  constitute  the  floral  envelope  and  are  not  essential  to  the  making  of  seeds. 
In  many  kinds  of  plants  the  flower  has  no  envelope. 

NOTE  5.  The  central  organ  is  the  pistil  and  may  consist  of  one  or  several  carpels  (which  can  usually  be  recognized 
by  ridges  running  lengthwise).  The  main  parts  of  the  pistil  are  the  ovary,  or  seed-bearing  chamber,  usually  the  thickest 
part  and  at  the  base ;  the  stigma,  or  tip ;  and  the  part  connecting  stigma  with  ovary,  or  the  style. 

NOTE  6.  The  stalklike  or  threadlike  structures  with  little  knobs,  surrounding  the  pistil,  are  the  stamens.  The  stalk 
is  called  the  filament,  and  the  pollen-case  at  the  top  is  the  anther. 

Record.  Make  diagrams  to  illustrate  the  structure  of  the  whole  flower  and  the  arrangement  of  the 
parts ;  label  every  structure  named  in  the  notes. 

Make  a  cross  section  of  the  ovary,  and  draw,  showing  the  separate  carpels  and  the  area  carrying  the 
ovules,  which  are  to  become  the  seeds. 

NOTE  7.  The  surface  to  which  ovules  are  attached  is  called  the  placenta. 


1  A  complete  flower  is  one  that  has  a  floral  envelope  as  well  as  the  seed-making  organs. 

2  A  regular  flower  is  one  in  which  the  organs  of  each  circle  are  all  alike  as  to  form. 
8  A  perfect  flower  is  one  that  has  both  stamens  and  pistils. 

[124] 


EXERCISE  116  (Continued) 

Questions.    1.  How  many  sepals  are  there  ?  Are  they  separate  or  joined  ? 

2.  How  many  petals  are  there  ?  Are  they  separate  or  joined  ? 

3.  How  are  the  sepals  placed  with  relation  to  the  petals  ? 

4.  How  many  stamens  are  there  ?  Are  they  separate  or  joined  ? 

5.  How  are  the  stamens  placed  with  relation  to  the  petals  ? 

6.  How  is  the  anther  attached  to  the  filament  ? 

7.  What  is  there  about  the  anther  that  would  permit  the  pollen  to  get  out  ? 

8.  What  is  there  about  the  stigma  that  would  permit  pollen  spores  to  cling  to  it? 

9.  How  many  distinct  seed  chambers  are  there  in  the  ovary  ? 

10.  Are  the  seed  chambers  completely  partitioned  from  each  other  ? 

11.  How  many  rows  of  ovules  are  there  ? 

12.  Which  do  you  consider  the  essential  organs  of  the  flower  ?  Why  ? 

NOTE  8.    The  relation  of  pollen  to  seed-making  cannot  be  inferred  from  a  study  of  the  flower's  structure,  but  will  be 
studied  later. 


[125] 


EXERCISE  117 

Problem.    In  what  ways  may  flowers  differ  from  each  other  and  still  carry  on  the  work  of  seed-making  ? 

What  to  use.    Flowers  of  various  kinds  ;  magnifying  glass  ;  dissecting  needles. 

What  to  do.  Examine  one  flower  'at  a  time  and  note  in  what  ways  it  resembles  and  in  what  ways  it 
differs  from  the  first  flower  studied.  Check  up  the  sizes  and  shapes  of  the  several  organs,  their  markings, 
their  numbers,  and  their  arrangement. 

Record.  Describe,  following  the  questions  in  Exercise  116  and  using  diagrams.  Enter  the  name  of 
each  species  studied. 

NOTE.  In  some  species  of  plants  the  flowers  contain  peculiar  or  unusual  structures  not  mentioned  in  the  study.  Make 
a  record,  with  drawings  if  possible,  of  any  such  found. 


[126] 


EXERCISE  118 

Seeds  develop  from  ovules,  but  only,  as  a  rule,  after  protoplasm  from  the  pollen  reaches  and  fuses 
with  protoplasm  inside  the  ovule. 

Problem.    How  does  the  protoplasm  from  the  pollen  reach  the  inside  of  the  ovule  ? 

What  to  use.  Some  live  flowers  ;  slides  ;  dilute  sirup  (sugar  in  water,  about  three  per  cent) ;  moist 
chamber ;  section  cutter  or  razor ;  prepared  sections  of  ovules. 

What  to  do.  1.  Get  some  pollen  from  the  anthers  of  the  flower  to 'sprout  in  a  drop  of  sirup  on  a 
glass  slide  in  a  moist  chamber  (see  Exercise  115) ;  examine  with  the  microscope. 

NOTE.  The  nucleus  near  the  end  of  the  pollen  tube  is  the  male,  or  sperm,  nucleus,  which  is  to  unite  with  protoplasm 
in  the  ovule. 

2.  Examine  the  surface  of  the  stigma  to  see  (a)  how  pollen  grains  can  find  lodgment  on  it,  and 
(b)  what  would  make  pollen  grains  sprout  there,  forming  pollen  tubes. 

NOTE.  The  style  is  usually  either  hollow  through  the  middle  or  made  up  of  loose  tissue  through  which  a  pollen  tube 
readily  grows. 

3.  Examine  several  ovules  with  low  power  of  the  microscope,  to  find  the  micropyle  (see  Exer- 
cise 30)  through  which  the  pollen  tube  may  enter  the  ovule. 

4.  Examine  sections  of  ovule  and  note  the  large  cell  on  the  inside  —  the  embryo  sac,  inside  of  which 
the  new  plant,  or  embryo,  is  to  develop. 

NOTE.  The  original  nucleus  of  the  embryo  sac  divides  several  times.  One  of  the  resulting  nuclei  is  the  female,  or 
egg,  nucleus,  and  unites  with  the  sperm  from  the  pollen  tube. 

Record.    Draw  and  describe  the  structures  studied. 


Questions.    1.  How  does  the  protoplasm  of  the  pollen  spore  reach  the  ovule? 

2.  How  does  the  sperm  from  the  pollen  tube  get  to  the  embryo  sac  ? 

3.  What  is  likely  to  become  of  the  ovule  as  the  embryo  ripens  ? 

4.  How  is  the  developing  embryo  nourished  ? 


[127] 


EXERCISE  119 

The  transfer  of  pollen  from  the  anther  of  one  flower  to  the  stigma  of  another  is  in  most  cases 
brought  about  either  by  the  wind  or  by  insects. 

Problem.    What  is  there  about  flowers  that  makes  possible  the  distribution  of  pollen  by  the  wind  ? 

What  to  use.    A  magnifying  glass  and  a  pair  of  sharp  eyes. 

What  to  do.  Examine  the  pollen,  the  stigmas,  and  the  envelopes  of  many  different  wild  and  culti- 
vated plants  in  the  field,  and  note  the  probability  of  the  pollen's  being  easily  blown  from  the  anther, 
being  easily  carried  by  the  wind,  and  being  readily  caught  by  the  stigmas.  Compare  various  kinds  of 
flowers  to  note  differences  that  are  likely  to  be  significant  in  this  connection. 

Record.  Make  a  list  of  plants  that  you  consider  to  be  probably  wind-pollenated,  and  describe  the 
characteristics  that  lead  you  to  your  conclusions. 


NAMES  OF  PLANTS 


CHARACTER  OF  POLLEN 


CHARACTER  OF  STIGMA 


CHARACTER  OF  FLORAL  ENVELOPE 


[128] 


EXERCISE  120 

Problem.    What  is  there  about  flowers  that  makes  possible  the  distribution  of  their  pollen  by  insects? 

What  to  use.    As  in  previous  exercise. 

What  to  do.  Examine  the  stamens,  pollen,  stigmas,  and  envelope  of  many  different  wild  and 
cultivated  flowers,  looking  out  especially  for  flowers  around  which  insects  are  hovering.  Note  the  rela- 
tive position  of  the  anther  and  the  stigma  and  the  character  of  the  pollen  that  would  make  distribution 
by  insects  probable.  Note  what  there  is  about  the  structure  of  the  flower  as  a  whole  that  would  make 
the  visits  of  insects  likely. 

Record.  Make  a  list  of  plants  that  you  think  are  probably  insect-pollenated,  illustrate  by  drawings, 
and  describe  the  characteristics  that  lead  to  your  conclusions. 


NAMES  OF  PLANTS 

CHARACTER  OK 

POLLEN 

POSITION  OF  STIGMA 

CHARACTER  OF  FLORAL 
ENVELOPE 

PROBABLE  INSECT  VISITOR 

4 

Questions.    1.  What  practical  use  is  made  of  the  fact  that  insects  make  their  food  stores  out  of 
flower  nectar  ? 

2.  What  plants  secrete  nectar  without  getting  their  pollen  transferred  by  insects  ? 

3.  Can  you  find  insects  visiting  flowers  without  serving  as  pollen  carriers  ? 

4.  What  plants  with  odorous  and  conspicuous  flowers  are  pollenated  without  the  aid  of  insects  ? 


[129] 


EXERCISE  121 

When  the  ovary  ripens  into  a  seed-carrier,  the  ovary  and  certain  other  parts  of  the  flower  may  grow 
together  and  form  the  fruit. 

Problem.    What  structures  besides  the  ovary  are  represented  in  the  fruit  ? 

What  to  use.  Several  different  kinds  of  fruits,  including  fleshy  fruits,  pods,  grains,  berries,  etc. ; 
knife ;  magnifying  glass. 

What  to  do.  Examine  the  fruits  carefully  (first  externally,  then  in  cross  and  longitudinal  sections), 
to  discover  how  much  originated  from  the  ovary  or  other  part  of  the  pistil  and  what  remains  of  the 
receptacle,  of  the  calyx,  etc. 

NOTE.  In  the  composite  family  (to  which  the  sunflowers  belong),  as  well  as  in  some  other  families  of  plants,  there  is 
sometimes  formed  a  group  of  leaflike  scales  at  the  base  of  the  flower  cluster.  This  involucre  in  many  cases  becomes  fused 
into  a  more  or  less  adherent  part  of  the  fruit. 

Record.  Make  a  list  of  the  fruits  studied,  and  opposite  each  tell  (i)  what  parts  of  the  plant  have 
become  part  of  the  fruit,  and  (2)  what  functions  are  probably  performed  by  each  part. 


NAME  OF  FRUIT 


PARTS  OF  PLANT  OR  OTHER  STRUCTURES 
PRESENT  IN  FRUIT 


FUNCTIONS  OF  THE  DIFFERENT  PARTS 


Questions.    1.  What  changes  take  place  in  the  ripening  of  a  fruit  that  are  of  value  to  the  plant  or 
to  the  species  ? 

2.  What  changes  take  place  in  the  ripening  of  fruits  that  make  certain  ones  of  value  to  man  ? 

3.  What  are  some  of  the  uses  to  which  we  put  fruits  ? 

4.  What  are  some  important  differences  between  wild  and  domesticated  fruits  ? 


[130] 


EXERCISE  122 

From  the  viewpoint  of  a  race  of  plants  the  fruit  is  of  value  (i)  as  a  protection  to  the  young  plant 
until  it  can  be  safely  launched  away  from  "  home,"  and  (2)  as  an  aid  in  distributing  the  seeds  over  as 
wide  an  area  as  possible.  Since  plants  are  not,  as  a  rule,  organisms  that  are  capable  of  independent 
locomotion,  they  must  depend  upon  outside  moving  agencies  to  transport  them. 

Problem.     In  what  ways  are  fruits  and  seeds  adapted  to  wide  distribution  ? 

What  to  use.  Many  different  kinds  of  fruits  and  seeds  in  the  field,  woods,  or  garden  ;  some  to  study 
in  detail  in  the  laboratory. 

What  to  do.  Examine  the  fruits  and  seeds  to  see  what  there  is  about  them  that  fits  them  to  a  wide 
distribution.  Consider  what  agencies  in  their  environment  might  be  available  as  aids  in  distribution, 
and  what  processes  of  the  parent  plants  might  be  of  service. 

Record.  Make  a  list  of  distinct  types  of  fruits  or  seeds,  illustrating  different  modes  of  distribution, 
and  describe  their  modes  of  dissemination. 


NAMES  OF  PLANTS 

AGENCIES  AIDING  IN  DISTRIBUTION 

STRUCTURES  AND  OTHER  CHARACTERS  AND  THEIR 
RELATION  TO  THE  DISTRIBUTING  AGENCIES 

Example 

Cocklebur 

Moving  animals 

Spines  with  hooked  ends,  clinging  to  fur 

1 

2 

3 

4 

f 

5 

Questions.    1.  What  advantage  is  it  to  a  plant  to  produce  seeds? 

2.  What  advantage  is  it  to  a  plant  to  scatter  its  seeds  far  from  its  own  base  ? 

3.  Of  what  advantage  to  the  species  is  wide  distribution  ? 


[131] 


EXERCISE  123 

In  all  except  the  lowest  families  of  plants  there  are  two  modes  of  reproduction  and  two  distinct 
generations,  each  reproducing  in  its  own  way.  One  generation,  reproducing  by  means  of  sperms  and 
eggs,  is  called  the  sexual  generation  ;  the  other,  reproducing  by  means  of  spores,  is  called  the  sexless,  or 
asexual,  generation. 

Problem.    What  is  the  life  history  of  a  plant  having  alternation  of  sexual  and  asexual  generations  ? 

What  to  use.  Fresh  or  dried  moss  of  some  large  variety,  with  the  "fruit"  stalks,  complete;  some 
without  the  fruits ;  microscope  with  slides  etc. ;  magnifying  glass ;  section  cutter ;  prepared  micro- 
scopic slides. 

What  to  do.  1.  If  dry  material  is  used,  it  should  be- soaked  up  in  water.  Examine  the  plant  with- 
out fruit  and  note  its  main  parts  and  the  arrangement  and  character  of  the  "  leaves."  This  is  the 
sexual  generation.  Note  the  rosette  of  leaves  at  the  top.  Examine  several  specimens  with  the  glass 
to  find  structural  differences.  Make  longitudinal  sections  through  the  tips  of  several  specimens  and 
examine  with  the  microscope.  Compare  your  sections  with  the  prepared  ones. 

NOTE  i.  It  is  possible  to  find,  among  the  hairlike  growths  within  some  of  the  rosettes,  flask-shaped  organs,  the  arche- 
gonia,  each  containing  a  large  egg  cell  in  the  basal  portion  ;  and  in  other  rosettes,  club-shaped  structures,-  the  antheridia, 
each  of  which  produces  a  large  number  of  sperm  cells. 

2.  Examine  some  of  the  fruiting  specimens  and  note  the  stalk  and  the  spore  capsule  on  top,  the 
hood  over  the  capsule,  the  lid,  and  the  structure  of  the  mouth  after  the  lid  is  removed.  This  is  the 
asexual  generation.  Study  with  the  magnifying  glass  all  the  structures  named.  Make  cross  and 
longitudinal  sections  of  the  spore  case  and  study  with  the  microscope.  Compare  your  sections  with  the 
prepared  ones. 

NOTE  2.  Sperm  cells  swim  about  by  means  of  cilia,  and  some  find  their  way  down  the  neck  of  an  archegonium,  where 
one  unites  with  the  egg  cell.  The  fertilized  egg  cell  begins  at  once  to  develop  into  a  spore-bearing  individual,  absorbing 
practically  all  its  food  from  the  parent  plant  —  the  female  sexual  individual.  The  hood  on  top  of  the  spore  case  is  the 
upper  part  of  the  archegonium,  which  continues  to  grow  for  a  while  after  fertilization  takes  place. 

NOTE  3.  The  spore-bearing  (asexual)  individual  is  called  the  sporophyte.  The  gamete-bearing  (sexual)  individuals, 
bearing  the  sperm  or  eggs,  are  called  the  gametophytes. 


[132] 


EXERCISE  123  (Continued) 

Record.    Make  enlarged  drawings  to  show  the  following  structures : 

1.  Gametophyte  as  a  whole,  stalk,  "roots,"  "leaves." 

2.  Longitudinal  section  of  rosette  showing  archegonia. 

3.  Longitudinal  section  showing  antheridia. 

4.  Sporophyte  growing  out  of  gametophyte,  general  view. 

5.  Enlarged  view  of  spore  capsule,  with  hood  and  lid  separated. 

6.  Longitudinal  section  of  spore  capsule. 

7.  Microscopic  view  of  spores. 

NOTE  4.    In  the  mosses,  a  sporophyte  always  develops  from  a  fertilized  egg,  and  a  gametophyte  always  develops 
from  a  spore. 


Questions.    1.  What  are  the  most  striking  structural  differences  between  the  sporophyte  and  the 
gametophyte  in  the  moss  ? 

2.  Which  generation  is  the  better  food  producer  ?   Why  ? 

3.  Which  generation  contributes  more  to  a  wide  distribution  of  the  species  ?    How  ? 

4.  What  conditions  must  be  necessary  for  fertilization  ? 

5.  In  what  sense  is  the  gametophyte  dependent  upon  the  sporophyte  ? 

6.  In  what  sense  is  the  sporophyte  dependent  upon  the  gametophyte  ? 

7.  Which  generation  could  more  readily  live  an  independent  life  if  it  were  once  started  on  its 
way  ?    Why  ? 


[133] 


EXERCISE  124 

In  the  highest  plants  the  gametophyte  is  always  parasitic  on  the  sporophyte,  whereas  in  the  lower 
plants  (mosses)  the  sporophyte  is  parasitic  on  the  gametophyte. 

Problem.  Are  there  any  plants  in  which  the  two  generations  are  about  equally  self-sustaining  ? 

What  to  use.  Fern  plants,  complete,  with  fruiting  dots  ;  prothalli  of  fern  ;  magnifying  glass  ;  micro- 
scope with  slides  etc. 

What  to  do.  1.  Examine  the  fern  plant  and  note  structure  of  underground  stem,  roots,  leaf,  and 
spore  areas  on  underside  or  at  edge  of  frond.  Examine  spore  cases  and  spores  under  microscope,  noting 
especially  the  part  of  the  spore  case  that  is  related  to  the  scattering  of  the  spores. 

NOTE  r.   The  familiar  stage  of  the  fern  plant  is  the  sporophyte.    It  develops  from  a  fertilized  egg  and  bears  spores. 

2.  Examine  prothalli  under  the  microscope  as  well  as  with  magnifying  glass.  Study  under  surface  as 
well  as  upper.  Note  rhizoids,  like  root  hairs ;  archegonia  near  the  front  edge  and  antheridia  near  the 
hind  edge. 

NOTE  2.  The  prothallus  is  the  gametophyte ;  it  develops  from  a  spore.  Eggs  and  sperms  are  borne  on  one  individual. 
After  fertilization  the  egg  develops  into  a  sporophyte. 

Record.  Make  drawings  and  label  to  show  the  following  stages  and  structures  : 

1.  The  sporophyte  as  a  whole,  with  characteristic  leaves,  rootstock  (underground  stem),  and  absorbing 
organs. 

2.  The  fruiting  dots,  or  masses  of  spore  cases  :  microscopic  view  of  (a)  spore  case  entire  ;  (b]  spore 
case  broken ;  (c)  spores. 

3.  The  gametophyte  (upper  surface),  enlarged. 

4.  Lower  surface  of  gametophyte,  under  microscope  :  (a)  rhizoids ;  (&)  archegonia  ;  (c)  antheridia ; 
and,  if  possible,  (d)  egg  and  sperm  cells. 


[134] 


EXERCISE  124  (Continued) 


Questions.    1.  Which  do  you  consider  the  more  highly  developed  organism,  the  sporophyte  or  the 
gametophyte  ?    Why  ? 

2.  Could  the  sporophyte  perpetuate  itself  without  the  gametophyte  ?  Why  ? 

3.  Could  the  gametophyte  perpetuate  itself  without  the  sporophyte  ?  Why  ? 

4.  In  what  sense  is  the  sporophyte  dependent  upon  the  gametophyte  ? 

5.  In  what  sense  is  the  gametophyte  dependent  upon  the  sporophyte  ? 


[135] 


EXERCISE  125 

In  the  following  table,  list,  in  the  appropriate  spaces,  the  organs  or  structures,  tissues,  etc.  that  are 
distinctive  of  each  type  of  plant  —  that  is,  the  structures  present  in  one  generation  that  are  not  to  be 
found  in  the  alternate  generation.  For  example,  in  the  sporophyte  of  the  seed-bearing  plants  there  are 
flowers,  while  there  are  none  in  the  gametophyte. 


PRESENT  IN  SPOROPHYTE  BUT  NOT  IN  GAMETOPHYTE 


PRESENT  IN  GAMETOPHYTE  BUT  NOT  IN  SPOROPHYTE 


Of  mosses 


Of  ferns 


Of  seed  plants 


Questions.    1 .  How  does  the  mode  of  life  of  a  moss  sporophyte  compare  with  that  of  a  fern  sporophyte  ? 

2.  How  does  the  mode  of  life  of  a  moss  gametophyte  compare  with  that  of  a  violet  gametophyte  ? 

3.  What  is  there  in  a  moss  plant  to  correspond  to  a  flower  ? 

4.  How  many  kinds  of  gametophytes  are  there  in  a  moss  ?  in  a  fern  ?  in  an  apple  ? 

5.  What  is  there  in  a  tomato  plant  to  correspond  to  the  fruit  dots  of  a  fern  ? 


[136] 


EXERCISE  126 


Reproduction  by  means  of  gametes  and  reproduction  by  means  of  spores  seem  to  have  led  in  most 
families  of  plants  to  the  evolution  of  two  distinct  generations.  In  almost  all  the  familiar  species  of 
plants  the  spore-bearing  generation  has  become  not  only  more  conspicuous  in  size  but  more  highly 
specialized  in  the  number  and  variety  of  organs  and  tissues.  On  the  other  hand,  the  gamete-bearing 
generation  has  tended  to  become  reduced  to  a  microscopic  body,  simple  in  structure  and  parasitic  in  habit. 
In  the  following  table  sketch  and  describe  briefly  the  various  stages  in  the  life  history  of  the  types 
imed,  emphasizing  the  distinctive  traits  in  each  case. 


f— 

STAGES  AND  ORGANS 

A   Moss 

A  FERN 

A  SPERMATOPHYTE 

Fertilized  egg 

Sporophyte 

• 

. 

Spore  case 

. 

• 

Spore 

Gametophyte 

Gamete-bearers 
(male  and  female) 

Gametes 

[137] 


EXERCISE  127 

In  all  except  a  few  species  of  small  animals,  reproduction-  is  brought  about  by  the  fusion  of  a  sperm 
cell  with  an  egg  cell.  But  there  is  great  variation  in  the  number  of  individuals  produced  and  in  the 
relation  between  parent  and  offspring  after  the  discharge  of  the  gametes. 

From  prepared  specimens,  models,  and  charts  gather  the  information  needed  for  completing  the 
following  table,  giving  the  name  of  the  type  studied  in  each  case  : 


NUMBER  OF  OFFSPRING 

WHERE  FERTILIZATION 
TAKES  PLACE 

WHERE  DEVELOPMENT 
TAKES  PLACE 

WHAT  PARENTS  SUPPLY  FOR 
DEVELOPING  EMBRYO 

K         a 
2         1 
fe         g. 

§         I 

• 

• 

w         g. 

MAMMAL 
(Name) 

Questions.    1.  What  relation  is  there  between  the  number  of  gametes  discharged  and  the  number 
of  fertilized  eggs  that  reach  maturity  ? 

2.  What  connection  is  there  between  the  number  of  individuals  produced  and  the  amount  of  aid 
each  gets  from  the  parents  ? 

3.  Of  what  does  parental  care  consist  ?    Of  what  value  is  it  to  (a)  the  individual  and  to  (b)  the 
species  ? 

4.  What  connection  is  there  between  the  amount  of  care  the  individual  receives  and  his  chances 
of  maturing? 

5.  How  far  is  your  last  statement  true  of  human  beings  ? 


[138] 


EXERCISE  128 

Problem.    What  is  the  relation  of  light  to  the  growth  of  living  things  ? 

What  to  use.    Sterilized  petri  dishes  with  culture  media ;  black  paper. 

What  to  do.  Expose  two  petri  dishes  to  infection  by  dust  from  the  air.  Cut  a  hole  of  a  distinc- 
tive form  in  a  piece  of  black  paper.  Cover  one  dish  with  the  perforated  paper  and  one  with  whole 
paper.  Expose  both  to  bright  sunshine  at  room  temperature  or  warmer  for  twenty-four  hours. 

Record.  Examine  petri  dishes.  Make  diagram  showing  numbers  and  distribution  of  colonies  in 
both.  Tell  what  effect  the  sunshine  had  on  the  growth  of  the  bacteria. 


Questions.    1.  What  practical  use  can  be  made  of  the  fact  brought  out  by  this  experiment? 

2.  How  do  these  results  harmonize  with  what  we  know  about  the  need  that  plants  have  of  sunlight? 

3.  What  is  there  in  your  experience  with  animals  that  corresponds  to  these  results  ? 


[139] 


EXERCISE  129 


Many  of  the  activities  of  living  things  have  to  do  with  matters  that  interfere  with  life.  Conditions 
vary  from  one  region  to  another  and  from  season  to  season  ;  protoplasm  must  adjust  itself  to  these 
variations  in  space  and  time.  The  structures  and  habits  of  related  animals  and  plants  are  accordingly 
different  in  different  regions,  and  the  appearance  and  habits  of  one  species  vary  from  season  to  season. 

Problem.  What  are  some  of  the  differences  between  the  summer  and  the  winter  conditions  of 
organisms  ? 

What  to  do.  In  the  following  tables  indicate  briefly  what  is  distinctive  during  the  extreme  seasons 
for  five  types  of  plants  and  for  five  types  of  animals. 

PLANTS 


NAME  OF  ORGANISM 

WHAT  IT  HAS  OR  DOES 

In  summer  but  not  in  winter 

In  winter  but  not  in  summer 

Example 

Spirogyra 

Grows  ;  reproduces  ;  has  chlorophyl 
bands  ;  forms  zygotes 

Resting  stage  ;  encysted  cells 

1 

2 

3 

4 

5 

ANIMALS 


NAME  OF  ORGANISM 

WHAT  IT  HAS  OR  DOES 

In  summer  but  not  in  winter 

In  winter  but  not  in  summer 

Example 

Mosquito 

Flies  about  ;  reproduces  ;  adult  female 
anfi  wigglers  feed 

Adults  only  ;  sluggish,  resting  in  dark 
corners 

1 

2 

3 

4 

5 

[140] 


EXERCISE  129  (Continued) 

Questions.    1.  What  differences  besides  those  of  temperature  are  there  between  summer  and  winter? 

2.  How  do  these  other  differences  influence  the  behavior  of  plants  ? 

3.  How  do  these  other  differences  influence  the  behavior  of  animals  ? 

4.  How  does  the  season's  effect  upon  one  group  of  organisms  influence  other  organisms  ? 

5.  What  practical  use  is  made  of  the  fact  that  certain  organisms  are  inactive  at  low  temperatures  ? 

6.  How  does  low  temperature  probably  reduce  the  activity  of  protoplasm  ? 

7.  How  does  high  temperature  probably  reduce  the  activity  of  living  matter  ? 

8.  How  does  shortage  of  water  influence  the  activity  of  protoplasm  ? 

9.  What  practical  use  can  be  made  of  the  fact  that  a  shortage  of  water  reduces  protoplasm  activity? 
10.  What  practical  use  can  be  made  of  the  fact  that  organisms  change  their  habits  with  the  seasons  ? 


[141] 


EXERCISE  130 

The  rain  is  said  to  fall  alike  on  the  just  and  the  unjust ;  but  one  with  an  umbrella  may  save  her 
bonnet.  A  passenger  boat  sinks  and  throws  the  wise  and  the  foolish  into  the  water  ;  if  near  shore,  a 
few  may  swim  and  save  themselves. 

Give  five  examples  of  situations  in  which  some  plants  or  animals  are  successful,  while  others  fail, 
and  point  out  what  it  is  that  makes  the  difference. 


DESTRUCTIVE  SITUATION 

SOURCE  OF  ADVANTAGE 

Example 

A  severe  winter  ;  many  birds  perish 

Better  feathers  save  some 

1 

2 

3 

4 

5 

Give  five  examples  of  situations  in  which  plants  or  animals  are  destroyed  without  discrimination. 


Example 

A  forest  fire  destroys  plants  and  animals  without  discrimination 

1 

2 

3 

4 

5 

Questions.  1.  In  the  survivals  of  the  first  set  of  examples,  do  the  plants  or  the  animals  struggle 
with  one  another  or  with  outside  conditions  ? 

2.  What  qualities  would  help  plants  or  animals  to  escape  or  to  survive  a  forest  fire  ?  a  severe 
windstorm  ?  a  famine  ?  a  drought  ? 


[142] 


EXERCISE  131 

Problem.    What  is  the  influence  of  light  and  color  on  pigmentation  ? 

What  to  use.  A  living  fence  lizard,  chameleon,  toad,  snake,  or  fish.  Papers  of  various  colors 
and  shades. 

What  to  do.  By  means  of  the  papers  change  the  background  of  the  animal  in  various  ways,  giving 
several  minutes  for  each  possible  reaction.  Note  any  changes  that  take  place  in  the  appearance  of  the  animal. 


Questions.    1.  Does  the  animal  respond  more  readily  to  a»change  of  shade  (illumination)  or  to  a 
change  of  color  ? 

2.  Does  it  respond  more  readily  to  an  increase  or  to  a  decrease  in  illumination  ? 

3.  Can  different  parts  of  the  body  respond  in  opposite  ways  ? 

4.  Do  the  changes  depend  upon  the  animal's  seeing  the  colors  ? 

5.  How  does  temperature  affect  the  color  of  the  skin  ? 

6.  How  does  temperature  affect  the  response  of  the  animal  to  changes  in  the  background  ? 


[143] 


EXERCISE  132 

Study  of  protective  movements  and  activities. 

What  to  use.    Any  convenient  live  animal  in  an  aquarium,  cage,  or  vivarium. 

What  to  do.    Expose  the  animal  to  various  kinds  of  stimulation  or  disturbance.    Record  its  reaction. 

Contact  stimulation.    Touch  gently  with  a  straw  or  light  rod  in  different  parts  of  the  body. 

1 .  Does  the  animal  move  toward  or  away  from  point  of  contact  ? 

2.  Is  this  response  the  same  in  all  parts  of  the  body  ? 

3.  Which  is  more  sensitive  to  contact,  the  anterior  (forward)  or  posterior  (hind)  end? 

NOTE.    In  radially  symmetrical  animals,  such  as  starfish,  sea  anemones,  and  others,  we  cannot  distinguish  anterior 
and  posterior  regions,  but  we  may  speak  of  the  oral  (mouth)  region  or  surface  and  the  aboral  (away-from-mouth)  region. 

4.  Which  is  more  sensitive  to  contact,  the  dorsal  (back,  or  shoulder)  side  or  the  ventral  (under,  or 
belly)  side  ? 

5 .  Are  the  right  and  the  left  side  equally  sensitive  ? 

6.  What  does  the  animal  do  on  coming  in  contact  with  a  solid  in  the  course  of  its  movements  ? 


Sight  stimulation.    Bring  your  hand,  a  stick,  or  a  piece  of  paper  toward  the  animal,  from  different 
directions  and  at  different  speeds. 

i.  What  effect  does  the  sight  of  an  object  produce  in  the  behavior  of  the  animal  ? 
,  2,. ,  At  what  distance  does  an  approaching  object  set  up  responses  in  the  animal  ? 

3.  How  does  the  distance  vary  with  the  direction  from  which  the  animal  is  approached  ? 

4.  What  kind  of  reaction  does  a  reduction  of  illumination  (shadow)  produce  ? 

5.  What  kind  of  reaction  does  an  increase  of  illumination  produce  ? 

6.  How  does  the  response  to  rapidly  moving  objects  differ  from  that  to  slowly  moving  objects  ? 


[144] 


EXERCISE  132  (Continued) 

Sound  stimulation.    Try  low  sounds  of  various  kinds  ;  scratch  or  rub  the  table  with  the  jar ;  agitate 
the  water  gently. 

1 .  How  can  you  tell  that  your  animal  is  sensitive  to  sound  ? 

2.  Is  it  sensitive  to  vibrations  in  solids  or  liquids,  other  than  sounds  ? 


Questions.    1.  What  advantage  do  you  think  the  animal  gets  from  reacting  as  it  does  to  various 
disturbances  ? 

2.  In  a  given  situation,  does  the  animal  seem  to  choose  what  to  do  ? 

3.  Are  there  any  movements  that  could  be  considered  offensive  rather  than,  or  as  well  as,  defensive  ? 


Movements  of  plants.    If  a  sensitive  plant  is  available,  study  the  location,  the  kind,  and  the  intensity 
of  disturbance  necessary  to  set  up  the  characteristic  reaction. 
Describe  the  plant's  movements. 
Note  how  much  time  it  takes  to  recover  the  open  position. 


Questions.    1.  Does  illumination  affect  the  sensitiveness? 

2.  What  benefit  does  the  plant  seem  to  derive  from  the  reaction  to  this  disturbance  ? 


[145] 


EXERCISE  133 

In  animals  that  have  two  or  more  similar  parts  (or  pairs  of  structures)  arranged  from  front  to  rear, 
such  as  vertebrae,  rings  of  a  worm,  paired  appendages,  etc.,  these  parts  are  considered  to  be  homologous, 
or  of  identical  origin.  Among  backboned  animals  and  among  arthropods  (insects,  crustaceans,  spiders, 
etc.),  where  the  appendages  are  numerous,  it  is  possible  to  find  species  that  show  one  or  more  special 
modifications  of  structure  related  to  protection. 

In  some  suitable  specimen  (for  example,  grasshopper,  crayfish,  crab,  beetle,  frog,  cat,  etc.)  study  the 
homologous  structures,  to  find  in  what  ways  any  of  them  show  adaptation  to  protection  of  the  individual. 

Record  your  findings,  using  diagrams  to  bring  out  the  differences  between  the  protecting  structures 
and  the  homologous  structures  that  are  not  protecting. 


[146] 


EXERCISE  134 

Find  and  draw  an  object  showing  the  results  of  the  activities  of  some  animal,  which  bring  about  the 
protection  of  the  animal  itself,  or  of  the  offspring,  against  either  (a)  unfavorable  conditions  or  (d)  its 
enemies. 


Questions.    1.  How  can  you  tell  that  the  activities  represented  are  really  protective? 
2.  What  human  activities  correspond  to  those  represented  in  your  specimen  ? 


[147] 


EXERCISE  135 

Problem.    How  does  the  natural  fall  of  leaves  differ  from  the  breaking  off  of  leaves  ? 

What  to  use.  Twigs  of  deciduous  trees  bearing  leaves  and  showing  old  leaf  scars  ;  magnifying  glasses  ; 
microscope ;  prepared  slide. 

What  to  do.  Study  several  of  the  old  leaf  scars.  Break  off  one  or  two  leaves  near  the  base  of  the 
petiole  (leafstalk)  and  study  the  scars  left.  Study  sections  through  base  of  petiole  with  microscope. 

Record.  Make  a  large  drawing  of  a  typical  natural  scar  and  of  one  resulting  from  tearing  off  the  leaf. 
Make  a  drawing  of  section  through  the  scission  (splitting)  layer  as  seen  with  the  microscope. 


Questions.    1 .  What  region  of  the  petiole  is  most  easily  broken  ? 

2.  What  marks  the  region  that  separates  when  the  leaf  falls  ? 

3.  How  does  the  surface  of  the  natural  scar  differ  from  that  of  the  artificial  scar  ? 


[148] 


EXERCISE  136 

The  forest  is  said  to  conserve  the  water  on  the  hillside  not  only  through  the  shielding  of  the  soil 
against  the  downpour  and  against  evaporation,  and  through  the  action  of  the  roots,  but  also  through 
the  formation  of  the  mulch,  consisting  of  decaying  leaves  and  other 
organic  matter. 

Problem.  What  is  the  relation  of  the  mulch  to  the  removal  of  rain 
water  ? 

What  to  use.  Two  funnels  of  the  same  size ;  two  test  tubes  or 
bottles  of  the  same  size  ;  sand  ;  forest  mulch  ;  absorbent  cotton  ;  water ; 
supports  for  the  funnels. 

What  to  do.  Plug  the  funnels  loosely  with  cotton  ;  fill  to  within 
an  inch  of  the  top  with  sand  ;  cover  surface  in  one  funnel  with  mulch. 
Place  a  bottle  or  test  tube  under  each  funnel  and  pour  the  same  quantity 
of  water  on  top  of  each. 

Record.    After  a  few  minutes  note  the  amount  of  water  that  has 

come  through  the  soil  in  the  two  funnels ;  what  does  the  result  show  regarding  the  relation  of  the 
mulch  to  the  water  flow  ? 


Questions.    1.   How  would  you  determine  the  drainage  quality  of  different  kinds  of  soil? 

2.  Where  would  mulch  be  produced  in  the  largest  quantity  ? 

3.  In  what  way  would  a  mulch  be  of  value  on  a  farm  or  in  a  garden  ? 

4.  Why  cannot  the  natural  soil  cover  serve  as  a  mulch  in  the  cultivated  fields  ? 

5.  In  what  rivers  has  the  flow  of  water  been  affected  by  the  cutting  down  of  forests  ? 


[149] 


EXERCISE  137 

Problem.    Do  commercial  mouth  washes,  as  ordinarily  used,  destroy  bacteria  ? 

What  to  use.  Three  squads  of  experimenters  ;  four  sets  of  sterilized  culture  dishes ;  commercial 
mouth  washes ;  water. 

What  to  do.  Leave  one  set  of  culture  dishes  unexposed  for  control  (a).  One  set  of  pupils  rinse 
mouth  with  a  teaspoonful  of  water,  and  each  throw  the  rinsing  into  a  separate  culture  dish  (b) ;  the 
second  set  of  pupils  wash  mouth  with  plain  water,  then  rinse  with  a  teaspoonful  of  water  and  save  rins- 
ing in  culture  dishes  (c) ;  the  third  set  wash  mouth  with  commercial  mouth  wash,  then  rinse  with  a 
teaspoonful  of  water  and  throw  rinsing  into  culture  dishes  (d] ;  label  all  dishes  —  names,  dates,  wash 
used,  etc.  —  and  set  aside  in  same  temperature,  illumination,  etc. 

Record.  Report  average  number  of  colonies,  or  spots,  in  each  set  of  dishes.  Compare  results  and 
record  conclusions. 


a.  CONTROL 

b.  WATER  RINSING 

c.  RINSING  AFTER  WATER 

d.  RINSING  AFTER  WASH 

•" 

Questions.    1.  In  what  way  are  commercial  mouth  washes  supposed  to  produce  their  results? 
2.  In  what  other  ways  can  the  desired  results  be  produced  ? 


[150] 


EXERCISE  138 

Vinegar  is  made  by  the  souring  of  cider  or  wine. 

Problem.    Have  microorganisms  anything  to  do  with  the  making  of  vinegar  ? 

What  to  use.  Hard  cider  or  wine  (made  by  allowing  strained  apple  juice  or  grape  juice  to  stand 
uncovered  in  a  moderately  warm  place  for  several  days)  ;  phenol,  formalin,  or  some  other  antiseptic ; 
litmus  paper ;  bottles. 

What  to  do.  Divide  the  cider  into  two  parts.  Leave  both  bottles  open  for  several  hours  or  over- 
night. Into  one  pour  a  few  drops  of  antiseptic ;  shake  up  or  stir.  Close  both  bottles  loosely  with 
cotton  plugs. 

After  twenty-four  hours,  test  both  with  litmus  paper,  and  smell.  Test  thus  at  intervals  until  you 
are  sure  you  have  vinegar. 

Record.   Describe  results  and  explain  the  difference  between  the  behaviors  in  the  two  bottles. 


Questions.    1.  Why  not  destroy  microorganisms  in  this  experiment  by  boiling  the  cider  instead  of 
poisoning  it  ? 

2.  Why  not  put  poison  into  sweet  cider  to  prevent  yeast  from  fermenting  it  into  hard  cider  ? 

3.  Why  not  boil  fluids  containing  alcohol  to  prevent  their  turning  sour  ? 


[151] 


EXERCISE  139 

The  spread  of  various  disease  germs  has  been  charged  against  the  common  house  fly. 

Problem.    Does  the  fly  actually  distribute  germs? 

What  to  use.  Sterilized  culture  dishes ;  living  flies  caught  in  various  localities ;  small  scissors ; 
clean  hands. 

What  to  do.  After  catching  the  flies  with  clean  hands,  snip  off  the  wings.  Place  one  such  fly  in 
each  culture  dish.  Save  one  or  more  dishes  for  control.  Apply  fingers  of  the  clean  hands  to  the 
gelatin  or  agar  in  other  dishes.  Label,  and  leave  for  twenty-four  hours  or  more. 

Record.  Note  the  number  and  arrangement  of  colonies  in  each  dish.  Describe  results,  draw  your 
conclusions,  and  give  reasons. 


Questions.    1.  How  can  you  tell  that  any  of  the  growths  were  due  to  disease  germs? 

2.  What  is  the  idea  of  handling  flies  with  clean  hands  ? 

3.  Why  cut  off  the  flies'  wings  ? 


[152] 


EXERCISE  140  -  FIELD  EXERCISE 

Make  a  diagram  representing  an  area  of  about  two  acres  or  a  city  block  in  your  neighborhood,  and 
indicate  on  it  the  location  of  every  spot  or  object  in  which  flies  do  or  may  breed. 


Questions.    1.  What  can  be  done  to  remove  these  breeding  places  ? 

2.  Who  is  responsible  for  their  removal  ? 

3.  Who  should  take  action  to  get  the  responsible  persons  to  remove  them  ? 

4.  At  what  points  in  the  life  history  of  the  fly  is  it  best  to  attack  it  for  the  purpose  of  extermi- 
nation ?  Why  ? 


[153] 


EXERCISE  141  -  FIELD  EXERCISE 

Make  a  diagram  representing  an  area  of  about  two  acres  or  a  city  block,  and  indicate  on  it  every 
spot  or  object  in  which  mosquitoes  do  or  may  breed. 


Questions.    1.  Which  of  these  breeding  places  can  be  removed  by  the  individual  owner  or  tenant? 

2.  Which  ones  require  the  cooperation  of  several  neighbors  ? 

3.  Which  ones  depend  upon  the  whole  community  or  officials  ? 

4.  What  recommendations  would  you  make  for  ridding  the  neighborhood  of  mosquitoes  ? 

5.  At  what  points  in  the  life  history  of  the  mosquitoes  is  it  best  to  attack  them  for  purpose  of 
extermination  ?  Why  ? 


[154] 


EXERCISE  142 

Various  insects  are  charged  with  destroying  things  and  material  of  value  to  human  beings.  Find 
some  object  or  material  that  shows  the  injurious  action  of  insects.  Find  out  what  insect  caused  the  mis- 
chief. Find  out  all  you  can  about  the  life  history  of  the  insect.  Make  drawings  of  the  various  stages, 
and  of  the  injured  material.  Indicate  the  sources  of  your  information. 


Questions.    1.  During  what  stage  of  life  does  the  insect  carry  on  injurious  activities? 

2.  What  is  the  relation  of  these  activities  to  the  insect's  life  ? 

3.  At  what  stage  in  its  life  history  is  the  insect  most  easily  combated  ? 

4.  What  methods  may  be  used  to  fight  this  insect  ? 


[155] 


EXERCISE  143 

Birds  have  come  to  be  recognized  as  of  such  great  value  to  mankind  that  it  is  no  longer  considered 
right  to  kill  them  either  for  the  fun  of  getting  the  better  of  them  or  for  the  satisfaction  of  displaying 
their  plumage.  We  can,  however,  have  just  as  much  fun,  and  get  other  benefits  besides,  if  we  use  our 
ingenuity  for  "  shooting  "  them  with  a  camera  or  for  "capturing  "  them  by  means  of  suitable  nesting  boxes 
or  by  means  of  food  placed  where  they  will  come  for  it  regularly  without  losing  their  liberty. 

If  you  have  a  camera,  show  that  you  are  smarter  than  the  birds  by  catching  one  when  he  is  not 
looking,  and  bring  back  a  good  photograph  as  evidence  of  your  prowess. 

"  Capture  "  a  bird  in  one  of  the  ways  suggested,  and  make  a  report  on  your  undertaking  and  its  results. 


Questions.    1.  What  is  the  name  of  your  prize  ? 

2.  How  does  the  bird  use  its  legs  ? 

3.  What  is  the  principal  food  of  this  bird  ? 

4.  Of  what  material  does  it  build  its  nest  ? 

5.  How  many  young  are  usually  reared  at  one  time  ? 

6.  Are  the  young  able  to  care  for  themselves  as  soon  as  hatched  ? 


[156] 


EXERCISE  144 

Problem.  How  near  alike  are  the  individuals  or  the  corresponding  organs  of  individuals  of  the 
same  kind  ? 

What  to  use.  A  hundred  or  more  persons,  flowers,  leaves,  hands',  plants,  or  other  convenient  indi- 
viduals or  organs  of  the  same  kind ;  a  ruler  divided  into  millimeters  or  into  tenths  of  an  inch,  or  some 
other  suitable  measuring  instrument  —  for  example,  a  dynamometer. 

What  to  do.  Count  the  stamens  of  a  hundred  buttercups,  the  ray  flowers  of  a  hundred  daisies  or 
asters,  or  the  ribs  on  a  hundred  elm  or  beech  leaves ;  or  measure  the  lengths  of  a  hundred  beans, 
corn  grains,  eggs,  or  seedlings,  or  the  chest  expansion,  grip  (right  and  left  hands),  or  circumference 
of  arms.1 

Record.  Make  a  table  showing  the  number  of  individuals  for  each  count  or  measurement.  Make 
a  graphic  diagram  to  show  the  distribution  of  the  variations  in  count  or  measurement  (cf.  Fig.  234  o£ 
textbook).  Describe  what  you  have  found. 


Questions.    1.  How  do  you  account  for  the  differences  that  you  find  ? 

2.  What  striking  examples  of  individual  variation  have  come  to  your  notice  ? 

3.  What  is  the  practical  importance  of  the  fact  that  no  two  human  beings  are  exactly  alike  ? 


1  It  is  possible  that  the  school  records  can  furnish  a  hundred  measurements  of  some  kind  (for  example,  chest  expansion),, 
which  may  be  made  to  serve. 

[157] 


EXERCISE  145 


When  a  parent  is  "  pure  "  (either  dominant  or  recessive)  with  respect  to  any  character,  all  the  germ 
cells  will  carry  the  determiner  for  that  one  character ;  but  in  a  mixed,  or  hybrid,  parent  half  the  germ 
cells  will  carry  the  dominant  determiner  and  half  will  carry  the  recessive  determiner. 

Problem.  What  are  the  chances  of  combining  recessive  and  dominant  determiners  from  two  parents 
Xhat  are  both  of  mixed  composition  ? 

What  to  use.  Two  bags,  each  containing  100  white  beans  to  represent  recessive  (R)  and  100  beans 
that  have  been  dipped  in  ink  to  represent  dominant  (D),  well  shaken  up. 

What  to  do.    Draw  pairs  of  beans,  one  from  each  bag,  sixteen  times  and  record  the  drawings. 


FATHER 


MOTHER 


APPEARANCE  OF  OFFSPRING  1 


10 


11 


12 


13 


14 


15 


16 


1  If  any  dominant  determiner  is  present,  the  offspring  appears  dominant ;  if  no  dominant  determiner  is  present,  the  offspring 
appears  recessive. 

[158] 


EXERCISE  145  (Continued) 

Record.    What  is  the  proportion  of  dominant  from  both  parents  ? 

What  is  the  proportion  of  recessive  from  both  parents  ? 

What  is  the  proportion  of  dominant  from  father  and  recessive  from  mother  ? 

What  is  the  proportion  of  dominant  from  mother  and  recessive  from  father  ? 

What  proportion  of  the  whole  offspring  is  pure  ? 

What  proportion  of  the  pure  is  dominant  ? 

What  proportion  of  the  pure  is  recessive  ? 

What  proportion  of  the  whole  offspring  is  mixed,  or  hybrid  ? 

What  proportion  of  the  hybrid  is  dominant  ? 

What  proportion  of  the  hybrid  is  recessive  ? 

What  proportion  of  all  is  dominant? 

What  proportion  of  the  dominant  is  pure  ? 


Questions.    1 .  Why  are  recessives  always  pure  ? 

2.  Which  characters  are  more  valuable  to  a  species,  the  dominant  or  the  recessive  ? 

3.  What  value  would  it  be  to  know  whether  a  given  human  trait  is  dominant  or  recessive  ? 

4.  How  would  you  find  out  the  chances  for  the  appearance  of  any  combination  of  characters  where 
there  are  two  alternative  pairs  ? 


[159] 


LABORATORY  SUPPLIES 


The  items  listed  below  will  suffice  for  the  demonstrations  and  for  the  laboratory  work  of  ten  pupils. 
For  larger  classes  order  proportionately  of  the  items  starred.  In  many  cases  suitable  substitutes  can  be 
obtained  or  made  by  teacher  and  pupils.  For  example,  satisfactory  alcohol  lamps  may  be  made  of  old 
bottles ;  tin  cans  and  jelly  glasses,  pickle  bottles,  and  other  containers  can  be  put  to  work  in  place  of 
expensive  vessels ;  and  so  on.  At  the  end  of  the  list  are  some  useful  directions  for  preparing  various 
solutions  etc. 


GLASSWARE 
i  aquarium,  1 2-liter 

*  i  o  battery  jars,  2-qt. 

*  10  beakers,  6o-cc. 

*  10  beakers,  i2o-cc. 

*  10  beakers,  250-00. 

i  large  bell  jar,  open  top,  with  cork 

*  2  doz.  bottles,  8-oz.,  wide-mouth,  with  corks  to  fit 

*  5  doz.  bottles,  4-oz.,  wide-mouth 

*  2  doz.  corks  to  fit  above 

*  2  sets  reagent  bottles  marked  : 

Hydrochloric  Acid 
Nitric  Acid 
Ammonia 
Fehling's  solution 
Acetic  Acid 
Limewater 
Tincture  Iodine 

*  10  cylinders,  500-0:.  or  rooo-cc.,  graduated 

*  10  flasks,  25o-cc. 

*  i  o  funnels,  3-in. 

1  crucible  30-0:.,  porcelain 

2  doz.  evaporating  dishes,  8o-cc.,  porcelain 

*  2  doz.  Petri  dishes 
i  box  cover  glasses 

i  gross  glass  slides 

*  10  magnifiers,  pocket,  double 
i  lens,  double  convex 

*  i  doz.  medicine  droppers 

*  3  thermometers,  —  10  to  +  1 50  C. 

*  10  thistle  tubes 

*  4  Ib.  glass  tubing,  assorted  sizes 

*  ^  Ib.  capillary  tubing 

*  4  doz.  tumblers 

*  i  gross  test  tubes,  6"  x  -|" 

*  3  doz.  quart  preserving  jars 

*  i  doz.  pint  preserving  jars 

APPARATUS 

i  trip  balance  with  weights 

*  i  doz.  agate  pans,  lo-in. 

*  6  sets  blocks,  wooden  cubes 
I  blowpipe,  large 

i  brush,  fine  camel's-hair 
*•£  doz.  brushes,  test-tube 

*  10  Bunsen  burners  or  alcohol  lamps 

*  10  mirrors,  small 

*  10  mirrors,  large 

*  5  pairs  dividers 


i  set  cork-borers 
i  egg-beater 
i  exhaust  pump 
i  file,  triangular 

*  5  microscopes,  compound,  double  nosepiece 

*  i  doz.  dissecting  needles 

*  5  ring  stands  with  rings  and  clamps 
i  section-cutter,  hand 

*  10  dissecting  scalpels 

*  10  pairs  dissecting  scissors 

i  storage  battery  or  6  dry  cells 

*  10  test-tube  racks 
i  tape  measure 

*  i  doz.  paper  scales,  150  cm.  divided  to  mm. 
i  triangle,  pipestem 

i  water  bath  or  double  boiler 

1  Arnold  sterilizer 

*  5  pieces  wire  gauze 

*  3  ft.  rubber  tubing,  -^-in. 

*  3  ft.  rubber  tubing,  T\-in. 

*  3  ft.  rubber  tubing,  ^-in. 

*  3  ft.  rubber  tubing,  T\-in. 

*  25  ft.  rubber  tubing  for  gas  burners 

*  i  doz.  rubber  stoppers,  No.  3,  i  hole 

*  i  doz.  rubber  stoppers,  No.  3,  2  holes 

*  i  doz.  rubber  stoppers,  No.  4,  I  hole 

*  i  doz.  rubber  stoppers,  No.  4,  2  holes 

*  \  doz.  rubber  stoppers,  No.  5,  i  hole 

*  \  doz.  rubber  stoppers,  No.  5,  2  holes 

*  2  doz.  rubber  stoppers,  No.  3 

CHEMICALS  AND  SUPPLIES 

*  2  doz.  small  blotters 

2  large  blotters,  blue  or  green 

*  i  doz.  candles,  short  sizes 

*  i  Ib.  absorbent  cotton 

*  i  package  filter  paper,  5-in. 
i  quire  filter  paper,  gray 

*  i  doz.  boxes  matches 
i  package  splints 

*  4  oz.  rubber  bands,  ^  in.  x  4  in. 
i  stick  sealing  wax 

i  gal.  alcohol,  grain 

4  gal.  alcohol,  wood  or  denatured 

i  Ib.  acetic  acid 

\  Ib.  alum,  potassium 

4  oz.  ammonium  nitrate 

1  Ib.  ammonium  chlorid,  granular 

2  Ib.  ammonium  hydroxid 

[160] 


8  oz.  barium  chlorid 

1  Ib.  carbon  bisulfid 

4  oz.  calcium  phosphate 
12  oz.  chloroform 
4  oz.  chrome  alum 
8  oz.  copper  sulfate 

2  oz.  diastase 
i  oz.  eosin 

i  Ib.  ether,  sulfuric 

i  Ib.  Fehling  solution,  tablets 

4  Ib.  formalin 

i  Ib.  grape  sugar 

1  gal.  gasoline 

2  Ib.  hyposulfite  of  soda 

1  Ib.  ferric  chlorid 

2  Ib.  hydrochloric  acid 
i  oz.  iodine 

i  Ib.  lampblack 

1  oz.  litmus  cubes  or  red  and  blue  litmus  paper 

2  Ib.  nitric  acid 

1  Ib.  manganese  dioxid 

2  oz.  magnesium  ribbon 
4  oz.  magnesium  sulfate 

4  Ib.  mercury,  redistilled 

1  oz.  pancreatin 

2  Ib.  sodium  carbonate 

1  Ib.  sodium  nitrite 

2  Ib.  common  salt 

i  Ib.  sodium  peroxid  (oxone) 

5  Ib.  sodium  silicate 

1  Ib.  starch 

2  oz.  phosphorus,  white 
i  oz.  phenolphthalein 

1  Ib.  potassium  chlorate,  granular 
t  Ib.  unslaked  lime 

[  Ib.  granulated  sugar 

2  oz.  vaseline 
i  Ib.  paraffin 
ro  Ib.  sawdust 
to  Ib.  sand 

I  bottle  India  ink 
i  bottle  red  ink 


LABORATORY   SUPPLIES   (Continued} 

LIVING  PLANTS 
Geranium 
Coleus 
Hydrangea 
Spirogyra 
Elodea  or  other  water  plants 


SEEDS 


Ib.  castor  bean 
Ib.  kidney  bean 
doz.  ears  corn  on  cob 
Ib.  cotton  seed 
doz.  horsechestnuts 
Ib.  Windsor  beans 
package  lettuce 
package  radish 
Ib.  pea 


Roots,  stems,  and  leaves  may  usually  be  collected,  together  with 
other  seeds  of  wild  plants,  fruits,  mosses,  ferns,  and  so  on. 
Fungi 
Lichens 
Seaweeds 

ANIMAL  MATERIAL 

*  i  doz.  living  earthworms 

*  i  doz.  living  frogs 

*  i  doz.  living  fish 

*  i  doz.  living  grasshoppers 
Crayfish 

Snails 

Beetles 

Moths 

Salamanders 

Sandworms 

Mosquitoes  and  other  insects,  in  all  stages 

Frog  and  toad  eggs 

Sea  urchins 

Starfish  etc. 

Preserved  and  mounted  specimens  as  opportunity  offers 


[161] 


CULTURE  MEDIA 

Beef  bouillon  for  growing  bacteria  may  be  made  with  2  tablespoonfuls  of  beef  extract  dissolved  in 
2  quarts  of  water.  Tube  in  sterilized  test  tubes ;  cork  with  cotton. 

Nutrient  agar-agar  is  the  best  medium  in  which  to  grow  bacteria.  It  may  be  prepared  from  the  fol- 
lowing materials :  1000  cubic  centimeters  of  water,  10  grams  of  salt,  10  grams  of  peptone, 
10  grams  of  beef  extract,  a  little  baking  soda,  and  10  grams  of  agar-agar.  If  agar-agar  cannot 
be  obtained,  use  100  grams  of  the  best  French  gelatin. 

Dissolve  the  beef  extract  in  the  1000  cubic  centimeters  of  water.  Cut  the  agar  into  pieces  and 
add  with  the  salt  and  peptone.  The  mixture  must  then  be  heated  in  a  double  boiler  to  cause  the 
agar  to  dissolve.  Next  add  enough  baking  soda  to  cause  red  litmus  paper  dipped  in  the  mixture 
to  turn  blue ;  that  is,  the  liquid  should  be  faintly  alkaline.  The  mass  is  then  filtered  within  a 
steam  sterilizer  by  placing  a  glass  funnel  in  the  mouth  of  an  Erlenmeyer  flask  and  one  or  two 
layers  of  absorbent  cotton  within  the  funnel  as  a  filter.  If  the  agar,  flask,  and  funnel  are  kept 
hot  within  the  sterilizer,  the  liquid  will  readily  pass  through  the  cotton.  A  special  hot-water  funnel- 
holder  may  be  purchased  to  do  away  with  the  use  of  a  sterilizer  in  filtering.  After  filtering,  the 
mouth  of  the  flask  should  be  closed  with  a  plug  of  absorbent  cotton.  Then  boil  in  a  double 
boiler  for  half  an  hour.  If  the  agar  mixture  is  not  clear,  it  should  be  filtered  through  cotton  a 
second  time.  If  care  has  been  taken,  the  nutrient  solution  is  now  ready  for  use  and  may  be  set 
aside  as  a  stock  solution. 

If  it  is  desired  to  make  a  nutrient  solution  for  molds,  omit  the  cooking  soda  and  add  a  few  drops 
of  dilute  hydrochloric  acid,  because  molds  grow  best  in  a  slightly  acid  medium,  while  bacteria  thrive 
in  a  slightly  alkaline  medium. 

To  prepare  the  nutrient  agar-agar  for  use  it  may  "be  poured  while  hot  into  petri  dishes  which  have 
been  previously  sterilized  with  dry  heat  for  several  hours  and  then  kept  in  a  dry  place  free  from 
dust.  It  is  well  to  sterilize  the  plates  once  or  twice  after  they  are  coated,  using  a  steam  sterilizer. 

Test  tubes  partially  filled  with  the  nutrient  jelly  are  also  useful.  Immediately  after  the  hot  jelly  is 
poured  into  the  test  tubes  the  latter  should  be  plugged  with  absorbent  cotton  and  then  placed  in 
the  steam  sterilizer. 

Fehlings  solution  (so  called  in  honor  of  its  discoverer)  can  be  purchased  in  the  form  of  tablets  or 

may  be  made,  and  when  kept  as  two  solutions  will  last  indefinitely. 
Add  to  35  grams  of  copper  sulfate  (blue  vitriol)   500  cubic  centimeters  of  water.     Put  aside  until  it 

is  completely  dissolved.    Call  this  Solution  A. 
To  1 60  grams  of  caustic  soda  and  173  grams  of  Rochelle  salt  add  500  cubic  centimeters  of  water. 

Dilute  to  i  liter.    Call  this  Solution  B. 
For  use,  mix  equal  parts  of  A  and  B. 

lodin  solution  is  made  by  simply  adding  a  few  crystals  of  the  element  iodin  to  95  per  cent  alcohol ; 
or,  better,  by  taking  I  gram  by  weight  of  iodin  crystals  and  |  gram  of  iodide  of  potassium  and 
dissolving  in  water ;  in  either  case  dilute  with  water  to  a  light  brown  color. 

Limewater  can  be  made  by  shaking  up  a  piece  of  quicklime  the  size  of  a  walnut  in  about  a  pint  of 
water.  Filter  the  limewater  into  bottles  and  it  is  ready  for  use.  Close  with  a  stopper  smeared 
with  vaseline. 

Phenolphthalein.  Dissolve  I  gram  in  7  grams  of  grain  alcohol ;  then  dilute  with  water.  If  the  solution 
appears  milky,  add  a  little  more  grain  alcohol. 

Hay  infusion  for  the  growth  of  protozoa,  normal  salt  solution,  and  other  aids  are  described  in  the 
"  Manual  of  Suggestions  for  Teachers." 

PRINTED    IN   THE   UNITED    STATES    OF   AMERICA 

[162] 


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